Ask Difference

Arc vs. Line — What's the Difference?

By Maham Liaqat & Fiza Rafique — Updated on April 15, 2024
An arc is a curved segment of a circle, emphasizing its shape and continuity, whereas a line is straight, extending infinitely in two directions without curvature.
Arc vs. Line — What's the Difference?

Difference Between Arc and Line

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Key Differences

An arc is defined as a portion of the circumference of a circle, making it inherently curved. In contrast, a line is a straight geometric figure with no curvature, extending infinitely in both directions.
In geometry, an arc represents a specific segment between two points along a circle's edge, used often to measure angles. On the other hand, a line is considered a fundamental element in geometry that defines the shortest distance between two points.
The length of an arc is determined by the radius of the circle and the angle it subtends at the center. Meanwhile, the concept of length for a straight line in practical applications usually refers to a line segment, which has two endpoints.
Visually, arcs are used to create smooth, rounded shapes and are integral to circular and spherical designs. Lines are more associated with creating boundaries, angles, and linear shapes in both artistic and technical drawings.
In mathematical notation, an arc is often described with its endpoints and the circle’s center or radius, highlighting its circular nature. A line is typically described by a linear equation or by specifying two points through which it passes.
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Comparison Chart

Definition

Curved segment of a circle's circumference
Straight path extending infinitely

Shape

Curved
Straight

Length Measurement

Based on radius and central angle
Distance between two points or infinite

Visual Representation

Part of circles and ovals
Edges, boundaries, and angles

Mathematical Representation

Specified by endpoints and circle details
Described by linear equations or two points

Compare with Definitions

Arc

A continuous part of the circumference of a circle.
The clock's hands moved over the arc marking the hours.

Line

A straight one-dimensional figure having no thickness and extending infinitely in both directions.
The artist drew a straight line on the canvas.

Arc

In mathematics, a segment of a circle defined by two endpoints.
We calculated the length of the arc for our geometry homework.

Line

A level or position in a structured form of communication or command.
He was second in line for the promotion.

Arc

A path that something follows in a curved trajectory.
The football followed a high arc after it was kicked.

Line

A row of people or things arranged in a straight path.
The students stood in line for their lunch.

Arc

A shape resembling a part of a circle.
The rainbow formed a perfect arc in the sky.

Line

A mark or stroke long in proportion to its breadth.
She drew several lines under the important dates.

Arc

A storyline that develops over part of a narrative.
The character's redemption arc was the highlight of the movie.

Line

A course of direction.
The ship sailed in a northeasterly line.

Arc

Something shaped like a curve or arch
The vivid arc of a rainbow.

Line

(Mathematics) A geometric object with neither width nor depth, typically straight and extending indefinitely.

Arc

(Mathematics) A segment of a circle.

Line

A thin continuous mark, as that made by a pen, pencil, or brush applied to a surface.

Arc

An electric arc.

Line

A similar mark cut or scratched into a surface.

Arc

(Astronomy) The apparent path of a celestial body as it rises above and falls below the horizon.

Line

A crease in the skin, especially on the face; a wrinkle.

Arc

A progression of events suggesting narrative cohesion, especially one that rises to a climax and settles to a final conclusion.

Line

A real or imaginary mark positioned in relation to fixed points of reference.

Arc

To form an arc.

Line

A degree or circle of longitude or latitude drawn on a map or globe.

Arc

To move or seem to move in a curved path
The stars that arc across the sky.

Line

The equator. Used with the.

Arc

(astronomy) That part of a circle which a heavenly body appears to pass through as it moves above and below the horizon.

Line

A border or boundary
The county line.

Arc

(geometry) A continuous part of the circumference of a circle (circular arc) or of another curve.

Line

A demarcation
A line of darker water beyond the reef.

Arc

A curve, in general. Category:en:Curves

Line

A contour or an outline
The line of the hills against the evening sky.

Arc

A band contained within parallel curves, or something of that shape.

Line

A mark used to define a shape or represent a contour.

Arc

(electrics) A flow of current across an insulating medium; especially a hot, luminous discharge between either two electrodes or as lightning.

Line

Any of the marks that make up the formal design of a picture.

Arc

A story arc.

Line

A cable, rope, string, cord, or wire.

Arc

(mathematics) A continuous mapping from a real interval (typically [0, 1]) into a space.

Line

(Nautical) A rope used aboard a ship.

Arc

(graph theory) A directed edge.

Line

A fishing line.

Arc

The three-point line.

Line

A clothesline.

Arc

(film) An arclight.

Line

A cord or tape used, as by builders or surveyors, for measuring, leveling, or straightening.

Arc

(ambitransitive) To move following a curved path.

Line

A pipe or system of pipes for conveying a fluid
Gas lines.

Arc

(transitive) To shape into an arc; to hold in the form of an arc.

Line

An electric-power transmission cable.

Arc

(intransitive) To form an electrical arc.

Line

A wire or system of wires connecting telephone or telegraph systems.

Arc

A portion of a curved line; as, the arc of a circle or of an ellipse.

Line

An open or functioning telephone connection
Tried to get a free line.

Arc

A curvature in the shape of a circular arc or an arch; as, the colored arc (the rainbow); the arc of Hadley's quadrant.

Line

A passenger or cargo system of public or private transportation, as by ship, aircraft, or bus, usually over a definite route.

Arc

An arch.
Statues and trophies, and triumphal arcs.

Line

A company owning or managing such a system.

Arc

The apparent arc described, above or below the horizon, by the sun or other celestial body. The diurnal arc is described during the daytime, the nocturnal arc during the night.

Line

A railway track or system of tracks.

Arc

To form a voltaic arc, as an electrical current in a broken or disconnected circuit.

Line

A particular section of a railway network
The Philadelphia-Trenton line.

Arc

Electrical conduction through a gas in an applied electric field

Line

A course of progress or movement; a route
A line of flight.

Arc

A continuous portion of a circle

Line

A general method, manner, or course of procedure
Different lines of thought.
Took a hard line on defense.

Arc

Something curved in shape

Line

A manner or course of procedure determined by a specified factor
Development along socialist lines.

Arc

Form an arch or curve;
Her back arches
Her hips curve nicely

Line

An official or prescribed policy
The party line.

Line

Often lines A general concept or model
A trilogy along the lines of the Oresteia.

Line

The condition of being in proper or aligned position
Is the table in line with the sofa?.

Line

A condition of agreement or correspondence
Your attitude is in line with mine. Is the policy in line with reality?.

Line

One's trade, occupation, or field of interest
What line of work are you in?.

Line

Range of competence
Not in my line.

Line

Merchandise or services of a similar or related nature
Carries a complete line of small tools.

Line

A group of persons or things arranged in a row or series
Long lines at the box office.
A line of stones.

Line

Ancestry or lineage.

Line

A series of persons, especially from one family, who succeed each other
A line of monarchs.
Comes from a long line of bankers.

Line

A strain, as of livestock or plants, developed and maintained by selective breeding.

Line

A sequence of related things that leads to a certain ending
A line of argument.

Line

An ordered system of operations that allows a sequential manufacture or assembly of goods at all or various stages of production.

Line

The personnel of an organization or a business who actually make a product or perform a service.

Line

A horizontal row of printed or written words or symbols.

Line

One of the horizontal scans forming a television image.

Line

A brief letter; a note
I'll drop you a line.

Line

A unit of verse ending in a visual or typographic break and generally characterized by its length and meter
A line of iambic pentameter.

Line

A unit of uninterrupted text spoken by an actor
Spent the weekend learning her lines.

Line

(Informal) Glib or insincere talk, usually intended to deceive or impress
He kept on handing me a line about how busy he is.

Line

A marriage certificate.

Line

A usually specified number of lines of prose or verse to be written out by a pupil as punishment.

Line

(Games) A horizontal demarcation on a scorecard in bridge dividing the honor score from the trick score.

Line

A source of information.

Line

The information itself
Got a line on the computer project.

Line

(Music) One of the five parallel marks constituting a staff.

Line

A sustained melodic or harmonic part in a piece
Strained to hear the tenor line.

Line

A formation in which elements, such as troops, tanks, or ships, are arranged abreast of one another.

Line

The battle area closest to the enemy; the front.

Line

The combat troops or warships at the front, arrayed for defense or offense.

Line

The regular forces of an army or a navy, in contrast to staff and support personnel.

Line

The class of officers in direct command of warships or of army combat units.

Line

A bulwark or trench.

Line

An extended system of such fortifications or defenses
The Siegfried line.

Line

A foul line.

Line

A real or imaginary mark demarcating a specified section of a playing area or field.

Line

A real or imaginary mark or point at which a race begins or ends.

Line

The center and two wings making up a hockey team's offensive unit.

Line

(Football) A line of scrimmage.

Line

(Football) The linemen considered as a group.

Line

(Informal) The odds a bookmaker gives, especially for sports events.

Line

The proportion of an insurance risk assumed by a particular underwriter or company.

Line

(Slang) An amount of powdered cocaine arranged in a thin, long strip for snorting.

Line

To mark, incise, or cover with a line or lines.

Line

To represent with lines.

Line

To place in a series or row.

Line

To form a bordering line along
Small stalls lined the alley.

Line

(Baseball) To hit (a ball) sharply so that it flies low and fast.

Line

To hit a line drive
Lined out to shortstop.

Line

To fit a covering to the inside surface of
A coat lined with fur.

Line

To cover the inner surface of
Moisture lined the walls of the cave.

Line

To fill plentifully, as with money or food.

Line

A path through two or more points (compare ‘segment’); a continuous mark, including as made by a pen; any path, curved or straight.
The arrow descended in a curved line.

Line

(geometry) An infinitely extending one-dimensional figure that has no curvature; one that has length but not breadth or thickness.

Line

A line segment; a continuous finite segment of such a figure.

Line

(graph theory) An edge of a graph.

Line

(geography) A circle of latitude or of longitude, as represented on a map.

Line

The equator.

Line

(music) One of the straight horizontal and parallel prolonged strokes on and between which the notes are placed.

Line

(cricket) The horizontal path of a ball towards the batsman (see also length).

Line

(soccer) The goal line.

Line

(motoring) A particular path taken by a vehicle when driving a bend or corner in the road.

Line

A rope, cord, string, or thread, of any thickness.

Line

A hose or pipe, of any size.
A brake line
The main water line to the house

Line

Direction, path.
The line of sight
The line of vision

Line

The wire connecting one telegraphic station with another, a telephone or internet cable between two points: a telephone or network connection.
I tried to make a call, but the line was dead.
A dedicated line;
A shared line
Please speak up, the line is very faint.

Line

A clothesline.
We need to take the clothes off the line. The news reported a front is coming in from the east, and we can expect heavy rain and maybe hail.

Line

A letter, a written form of communication.
Drop me a line.

Line

A connected series of public conveyances, as a roadbed or railway track; and hence, an established arrangement for forwarding merchandise, etc.
A line of stages
An express line

Line

(military) A trench or rampart, or the non-physical demarcation of the extent of the territory occupied by specified forces.

Line

The exterior limit of a figure or territory: a boundary, contour, or outline; a demarcation.

Line

A long tape or ribbon marked with units for measuring; a tape measure.

Line

(obsolete) A measuring line or cord.

Line

That which was measured by a line, such as a field or any piece of land set apart; hence, allotted place of abode.

Line

A threadlike crease or wrinkle marking the face, hand, or body; hence, a characteristic mark.

Line

; feature; figure (of one's body).

Line

A more-or-less straight sequence of people, objects, etc., either arranged as a queue or column and often waiting to be processed or dealt with, or arranged abreast of one another in a row (and contrasted with a column), as in a military formation.
The line forms on the right.
There is a line of houses.

Line

Ellipsis of line of battle

Line

(military) The regular infantry of an army, as distinguished from militia, guards, volunteer corps, cavalry, artillery, etc.

Line

(music) A series of notes forming a certain part (such as the bass or melody) of a greater work.

Line

A series or succession of ancestors or descendants of a given person; a family or race; compare lineage.

Line

A small amount of text. Specifically:

Line

A written or printed row of letters, words, numbers, or other text, especially a row of words extending across a page or column, or a blank in place of such text.
The answer to the comprehension question can be found in the third line of the accompanying text.

Line

A verse (in poetry).

Line

A sentence of dialogue, especially in a play, movie, or the like.
He was perfecting his pickup lines for use at the bar.
"It is what it is" was one of his more annoying lines.

Line

A lie or exaggeration, especially one told to gain another's approval or prevent losing it.
Don't feed me a line!

Line

Course of conduct, thought, occupation, or policy; method of argument; department of industry, trade, or intellectual activity.

Line

The official, stated position (or set of positions) of an individual or group, particularly a political or religious faction.
Remember, your answers must match the party line.

Line

(slang) Information about or understanding of something. (Mostly restricted to the expressions get a line on, have a line on, and give a line on.)
Judy gave me a line on a lawyer who's supposed to be the best in the business.

Line

A set of products or services sold by a business, or by extension, the business itself.
Line of business, product line
How many buses does the line have?
The airline is in danger of bankruptcy.

Line

(stock exchange) A number of shares taken by a jobber.

Line

Any of an ill-defined set of units of length, varying according to the country, discipline, industry, and date of application, commonly with no indication of the intended magnitude:

Line

(historical) A tsarist-era Russian unit of measure, approximately equal to one tenth of an English inch, used especially when measuring the calibre of firearms.

Line

One twelfth of an inch.

Line

One sixteenth of an inch.

Line

One fortieth of an inch.

Line

(advertising) agate line

Line

(historical) A maxwell, a unit of magnetic flux.

Line

The batter's box.

Line

(fencing) The position in which the fencers hold their swords.
Line of engagement

Line

(engineering) Proper relative position or adjustment (of parts, not as to design or proportion, but with reference to smooth working).
The engine is in line / out of line

Line

A small path-shaped portion or serving of a powdery illegal drug, especially cocaine.

Line

(obsolete) instruction; doctrine.

Line

(genetics) A population of cells derived from a single cell and containing the same genetic makeup.

Line

(perfusion line) a set composed of a spike, a drip chamber, a clamp, a Y-injection site, a three-way stopcock and a catheter.

Line

(ice hockey) A group of forwards that play together.

Line

(Australian rules football) A set of positions in a team which play in a similar position on the field; in a traditional team, consisting of three players and acting as one of six such sets in the team.

Line

A vascular catheter.
Patient had a line inserted
Line sepsis

Line

(South Korean idol fandom) A group of people born in a certain year (liners).
Maknae line; hyung line; 97 line

Line

(obsolete) Flax; linen, particularly the longer fiber of flax.

Line

(transitive) To place (objects) into a line (usually used with "up"); to form into a line; to align.
To line troops
Some more, please

Line

(transitive) To place persons or things along the side of for security or defense; to strengthen by adding; to fortify.
To line works with soldiers

Line

(transitive) To form a line along.

Line

(transitive) To mark with a line or lines; to cover with lines.
To line a copy book

Line

(railroading) To align (one or more switches) to direct a train onto a particular track.
The dispatcher lined the switches at Pickle interlocking for the freight turnout to clear the train into the passing track before the express arrived.

Line

To represent by lines; to delineate; to portray.

Line

(transitive) To read or repeat line by line.
To line out a hymn

Line

To hit a line drive; to hit a line drive which is caught for an out. Compare fly and ground.
Jones lined to left in his last at-bat.

Line

(transitive) To track (wild bees) to their nest by following their line of flight.

Line

(transitive) To measure.

Line

(transitive) To cover the inner surface of (something), originally especially with linen.
The bird lines its nest with soft grass.
To line a cloak with silk or fur
To line a box with paper or tin
Paintings lined the walls of the cavernous dining room

Line

To reinforce (the back of a book) with glue and glued scrap material such as fabric or paper.

Line

(transitive) To fill or supply (something), as a purse with money.
To line the shelves

Line

To copulate with, to impregnate.

Line

Flax; linen.

Line

The longer and finer fiber of flax.

Line

A linen thread or string; a slender, strong cord; also, a cord of any thickness; a rope; a hawser; as, a fishing line; a line for snaring birds; a clothesline; a towline.
Who so layeth lines for to latch fowls.

Line

A more or less threadlike mark of pen, pencil, or graver; any long mark; as, a chalk line.

Line

The course followed by anything in motion; hence, a road or route; as, the arrow descended in a curved line; the place is remote from lines of travel.

Line

Direction; as, the line of sight or vision.

Line

A row of letters, words, etc., written or printed; esp., a row of words extending across a page or column.

Line

A short letter; a note; as, a line from a friend.

Line

A verse, or the words which form a certain number of feet, according to the measure.
In the preceding line Ulysses speaks of Nausicaa.

Line

Course of conduct, thought, occupation, or policy; method of argument; department of industry, trade, or intellectual activity.
He is uncommonly powerful in his own line, but it is not the line of a first-rate man.

Line

That which has length, but not breadth or thickness.

Line

The exterior limit of a figure, plat, or territory; boundary; contour; outline.
Eden stretched her lineFrom Auran eastward to the royal towersOf great Seleucia.

Line

A threadlike crease marking the face or the hand; hence, characteristic mark.
Though on his brow were graven lines austere.
He tipples palmistry, and dinesOn all her fortune-telling lines.

Line

Lineament; feature; figure.

Line

A straight row; a continued series or rank; as, a line of houses, or of soldiers; a line of barriers.
Unite thy forces and attack their lines.

Line

A series or succession of ancestors or descendants of a given person; a family or race; as, the ascending or descending line; the line of descent; the male line; a line of kings.
Of his lineage am I, and his offspringBy very line, as of the stock real.

Line

A connected series of public conveyances, and hence, an established arrangement for forwarding merchandise, etc.; as, a line of stages; an express line.

Line

A circle of latitude or of longitude, as represented on a map.

Line

A long tape, or a narrow ribbon of steel, etc., marked with subdivisions, as feet and inches, for measuring; a tapeline.

Line

A measuring line or cord.
He marketh it out with a line.

Line

That which was measured by a line, as a field or any piece of land set apart; hence, allotted place of abode.
The lines are fallen unto me in pleasant places; yea, I have a goodly heritage.

Line

The proper relative position or adjustment of parts, not as to design or proportion, but with reference to smooth working; as, the engine is in line or out of line.

Line

Instruction; doctrine.
Their line is gone out through all the earth.

Line

The track and roadbed of a railway; railroad.

Line

A row of men who are abreast of one another, whether side by side or some distance apart; - opposed to column.

Line

A trench or rampart.

Line

Form of a vessel as shown by the outlines of vertical, horizontal, and oblique sections.

Line

One of the straight horizontal and parallel prolonged strokes on and between which the notes are placed.

Line

A number of shares taken by a jobber.

Line

A series of various qualities and values of the same general class of articles; as, a full line of hosiery; a line of merinos, etc.

Line

The wire connecting one telegraphic station with another, or the whole of a system of telegraph wires under one management and name.

Line

The reins with which a horse is guided by his driver.

Line

A measure of length; one twelfth of an inch.

Line

To cover the inner surface of; as, to line a cloak with silk or fur; to line a box with paper or tin.
The inside lined with rich carnation silk.

Line

To put something in the inside of; to fill; to supply, as a purse with money.
The charge amounteth very high for any one man's purse, except lined beyond ordinary, to reach unto.
Till coffee has her stomach lined.

Line

To place persons or things along the side of for security or defense; to strengthen by adding anything; to fortify; as, to line works with soldiers.
Line and new repair our towns of warWith men of courage and with means defendant.

Line

To impregnate; - applied to brute animals.

Line

To mark with a line or lines; to cover with lines; as, to line a copy book.
He had a healthy color in his cheeks, and his face, though lined, bore few traces of anxiety.

Line

To represent by lines; to delineate; to portray.

Line

To read or repeat line by line; as, to line out a hymn.
This custom of reading or lining, or, as it was frequently called "deaconing" the hymn or psalm in the churches, was brought about partly from necessity.

Line

To form into a line; to align; as, to line troops.

Line

A formation of people or things one beside another;
The line of soldiers advanced with their bayonets fixed
They were arrayed in line of battle
The cast stood in line for the curtain call

Line

A mark that is long relative to its width;
He drew a line on the chart
The substance produced characteristic lines on the spectroscope

Line

A formation of people or things one behind another;
The line stretched clear around the corner
You must wait in a long line at the checkout counter

Line

A length (straight or curved) without breadth or thickness; the trace of a moving point

Line

Text consisting of a row of words written across a page or computer screen;
The letter consisted of three short lines
There are six lines in every stanza

Line

A single frequency (or very narrow band) of radiation in a spectrum

Line

A fortified position (especially one marking the most forward position of troops);
They attacked the enemy's line

Line

The methodical process of logical reasoning;
I can't follow your line of reasoning

Line

A conductor for transmitting electrical or optical signals or electric power

Line

A connected series of events or actions or developments;
The government took a firm course
Historians can only point out those lines for which evidence is available

Line

A spatial location defined by a real or imaginary unidimensional extent

Line

A slight depression in the smoothness of a surface;
His face has many lines
Ironing gets rid of most wrinkles

Line

A pipe used to transport liquids or gases;
A pipeline runs from the wells to the seaport

Line

The road consisting of railroad track and roadbed

Line

A telephone connection

Line

Acting in conformity;
In line with
He got out of line
Toe the line

Line

The descendants of one individual;
His entire lineage has been warriors

Line

Something (as a cord or rope) that is long and thin and flexible;
A washing line

Line

The principal activity in your life that you do to earn money;
He's not in my line of business

Line

In games or sports; a mark indicating positions or bounds of the playing area

Line

(often plural) a means of communication or access;
It must go through official channels
Lines of communication were set up between the two firms

Line

A particular kind of product or merchandise;
A nice line of shoes

Line

A commercial organization serving as a common carrier

Line

Space for one line of print (one column wide and 1/14 inch deep) used to measure advertising

Line

The maximum credit that a customer is allowed

Line

A succession of notes forming a distinctive sequence;
She was humming an air from Beethoven

Line

A short personal letter;
Drop me a line when you get there

Line

A conceptual separation or demarcation;
There is a narrow line between sanity and insanity

Line

Mechanical system in a factory whereby an article is conveyed through sites at which successive operations are performed on it

Line

Be in line with; form a line along;
Trees line the riverbank

Line

Cover the interior of (garments);
Line the gloves

Line

Make a mark or lines on a surface;
Draw a line
Trace the outline of a figure in the sand

Line

Mark with lines;
Sorrow had lined his face

Line

Fill plentifully;
Line one's pockets

Line

Reinforce with fabric;
Lined books are more enduring

Common Curiosities

How do you measure the length of an arc?

The length of an arc is calculated using the radius of the circle and the central angle subtended by the arc.

What is the difference between a line segment and a line?

A line segment is part of a line that is bounded by two distinct end points, whereas a line extends infinitely in both directions.

What is an arc in geometry?

An arc in geometry refers to any portion of the circumference of a circle.

What defines a line in mathematical terms?

In mathematics, a line is described as an infinitely long, straight figure with no curvature.

Is an arc always part of a circle?

Yes, an arc is always a part of a circle, representing a segment of its circumference.

Can a line be curved?

No, by definition, a line cannot be curved; a curved line is called a curve or an arc.

What is the significance of a tangent line to a circle?

A tangent line to a circle is a straight line that touches the circle at exactly one point, illustrating the properties of circles and lines intersecting.

Can lines form shapes?

Yes, lines can form shapes when they connect at various points, creating polygons and other geometric figures.

What are the uses of arcs in real life?

Arcs are used in architecture, design, and engineering, particularly in structures requiring curves like bridges and arches.

What are practical applications of lines?

Lines are fundamental in construction, art, graphing, and many aspects of design, providing structure and direction.

What is the visual difference between an arc and a line?

Visually, an arc will always appear as a curved line, while a line is straight and does not curve regardless of perspective.

Are arcs used in calculating angles?

Yes, arcs are crucial in geometry for calculating angles, particularly in sectors and segments of circles.

How are arcs and lines represented in equations?

Arcs are often represented by their circular equations and defined by points and angles, whereas lines are represented by linear equations.

Do arcs have an end point?

Yes, arcs have two endpoints, which are the points where the arc begins and ends along the circle's circumference.

How can arcs and lines interact in a geometric space?

Arcs and lines can intersect or be tangent to each other, depending on their placement and equations in a plane.

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Author Spotlight

Written by
Maham Liaqat
Co-written by
Fiza Rafique
Fiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.

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