A Complete Geometry Symbols Study Guide (With Examples)

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What the most common geometry symbols mean and how to use them

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IN THIS ARTICLE

1 Angle: ∠

2 Measured Angle: ∡

3 Right Angle: ∟

4 Degree: deg or °

5 Line Segment: —

6 Line: ↔

7 Ray: →

8 Perpendicular: ⊥

9 Parallel: ∥

10 Equal Angle/Length: |, ||, |||, etc.

11 Congruent To: ≅

12 Similar To: ~

13 Triangle: △

14 Distance: |AB|

15 Pi: π

16 Spherical Angle: ∢

17 Arc: ⌒ or arc

18 Radians: rad or c

19 Gradians: grad or g

20 Prime (Arcminute): ′

21 Double Prime (Arcsecond): ″

22 Therefore: ∴

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Co-authored by David Jia and Dan Hickey

Last Updated: January 27, 2026 Fact Checked

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If you’re looking at your geometry homework and are totally stumped by all of the symbols and markings you see, you’re in the right place. We’ve put together an easy list of all the most common and important geometry symbols and what they mean (with examples of how to use them). Your next quiz is about to be a piece of cake!

Geometry Symbols Reference Chart

Geometry uses symbols to indicate the measurements of shapes or angles and the relationships between them. They’re shorthand ways of describing figures and are used in proofs, equations, and diagrams. Geometry symbols are largely universal since they convey foundational mathematical concepts.

Steps

1

Angle: ∠

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1. 
   The angle symbol ∠ denotes an angle formed by 2 rays or lines. When two rays or lines meet at a common endpoint (vertex), the amount of turn or rotation between them is called an angle, which can be measured in degrees or radians. The angle symbol represents this shape. Examples:

   • ∠B (where B is the vertex of 2 rays or lines)
   • ∠ABC = 60° (where ABC is a triangle and angle B is equal to 60°)
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2

Measured Angle: ∡

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1. 
   The measured angle ∡ indicates an angle with a known measurement. Think of this symbol as meaning “The measurement of angle __ is…”

   • It’s used when the measurement of the angle in degrees or radians is known (unlike the plain angle symbol ∠, which is more often used to represent abstract angles or geometric shapes). Examples:
   • ∡ABC = 30° (where ABC is a triangle and the angle at vertex B is 30°)
   • ∡A = 45°
   • Tip: You can still use the regular angle symbol ∠ to indicate a measurement. Typically, you’d write it as m∠A = 45° (where “m” means “measurement”).

3

Right Angle: ∟

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1. 
   The right angle symbol ∟ means an angle that is 90 degrees. A right angle is exactly 90 degrees (a quarter of 360 degrees, or a full circle). Think of it as a “perfect corner” where both lines forming the angle are perfectly perpendicular to each other. The symbol ∟ looks just like a right angle. Examples:

   • ∟A
   • ∟DEF (where DEF is a triangle and angle E is 90 degrees)
   • Tip: You’ll sometimes see a small square added to the vertex of the symbol (⦜), especially in diagrams, to further indicate the angle is 90 degrees.
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4

Degree: deg or °

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1. 
   The degree symbol ° (or abbr. deg) indicates a measurement in degrees. Degrees are a unit of measurement for the size of angles, and there are 360 degrees in a full circle (one full rotation). Examples:

   • ∡JKL = 57°
   • ∡JKL = 57deg (less common)
   • Prepping for a geometry test or quiz? Check out our article on how to get an A in geometry!

5

Line Segment: —

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1. 
   The line segment symbol — denotes a line with 2 known endpoints. Think of a line segment as a piece of a longer line. It represents a straight path between a clear starting point and endpoint (usually labeled with letters). In writing, the symbol goes above the 2 letters used to represent the endpoints. Examples:

   • AB (where A and B are the endpoints)
   • WP (where W and P are the endpoints)
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6

Line: ↔

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1. 
   The line symbol ↔ indicates an infinite line. Unlike a line segment, which has endpoints, lines go on forever. When the line symbol is placed above 2 letters, those letters represent points on the line, but not endpoints (as in, “the line contains points A and B”).

7

Ray: →

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1. 
   The ray symbol → indicates a line that starts at 1 point and extends to infinity. It’s written above 2 letters indicating points, like a line segment or line symbol. The first letter is the starting point of the line, which then passes through the second point and onward. Examples:

   • MN (where M is the starting point and N is a point along the ray)
   • RS (where R is the starting point and M is a point along the ray)
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8

Perpendicular: ⊥

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1. 
   The perpendicular symbol ⊥ shows that 2 lines intersect at a right angle. When perpendicular lines meet, they form a perfect 90-degree angle (a right angle). The symbol shows 2 such lines intersecting. A slash through the symbol ⟂̸ indicates the lines are not perpendicular. Examples:

   • CD ⊥ EF (line segment CD is perpendicular to line segment EF)
   • CD ⟂̸ EF (line segment CD is not perpendicular to line segment EF)

9

Parallel: ∥

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1. 
   The parallel sign ∥ shows that 2 lines or segments are parallel to each other. When lines are parallel, the distance between them is constant and does not change at any point (the lines will never intersect, even if extended into infinity). A slash through the symbol ∦ means the lines are not parallel. Examples:

   • CD ∥ EF
   • CD ∦ EF
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10

Equal Angle/Length: |, ||, |||, etc.

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1. 
   Matching sets of hatch marks show that 2 or more lines are congruent. Hatch marks (or tick marks) are short lines drawn on sides or angles to show that they’re equal. Different numbers of marks (single, double, triple, etc.) indicate different pairs of equal sides or angles within the same figure (or between congruent figures).

11

Congruent To: ≅

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1. 
   The congruent symbol ≅ means that 2 figures share the same size and shape. When figures are congruent, they have matching side lengths and identical angles, regardless of what position they’re in. Examples:

   • AB ≅ CD (line segments AB and CD are the same length)
   • ∠ABC ≅ ∠DEF (angles ABC and DEF have the same degree measurement)
   • △ABC ≅ △DEF (triangles ABD and DEF have the same number of sides, the same side lengths, and the same angles)
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12

Similar To: ~

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1. 
   The similarity symbol ~ shows that 2 figures are the same shape, but not the same size. Without the equals sign = underneath, the tilde symbol ~ means that 2 figures are the same shape and are proportionate to each other, but are not necessarily the same size. This means that the angle measurements will be the same between figures, even though the side lengths are scaled up or down. Examples:

   • △QPR ∼ △XYZ (triangle QPR is similar to triangle XYZ)
   • △ABC ∼ △EFG (triangle ABD is similar to triangle EFG)

13

Triangle: △

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1. 
   The triangle symbol △ indicates that a shape is a triangle. This one is pretty straightforward! It represents a triangle—a closed, 2D shape with 3 sides, 3 angles, and 3 vertices. Examples:

   • △LMN (triangle LMN)
   • △ABC ≅ △QRS (triangle ABD is congruent to triangle QRS)
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14

Distance: |AB|

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1. 
   The vertical distance lines | | indicate the distance between the points named inside. For example, |AB| refers to the distance between points A and B on a line (or the length of a segment between points A and B). Examples:

   • |CD| = 7 inches
   • |QP| = 4.3 centimeters

15

Pi: π

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1. 
   The pi sign π indicates the irrational number pi (3.151592654…). In geometry, pi is the ratio between the circumference and diameter of a circle. It’s an irrational number, meaning it can’t be expressed as a simple fraction with 2 integers; its decimal values just go on into infinity. Instead of writing out a long decimal number, use π instead. Examples:

   • c = π * d
   • π ≈ 3.14
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16

Spherical Angle: ∢

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1. 
   The spherical angle symbol ∢ indicates the intersection of 2 great circles of a sphere. A spherical angle is formed when 2 great circles (the largest possible circles on a sphere formed by a plane passing through its center) intersect. They’re measured by the plane angle formed by the tangents to the arcs at the point of intersection. If you’re studying advanced geometry or trigonometry, you’ll run into this symbol. Example:

   • ∢AOB = 30°
   • ∢HIJ = 89°

17

Arc: ⌒ or arc

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1. 
   The arc symbol ⌒ represents a smooth curve joining two endpoints on a circle. Similar to other line symbols, the arc symbol is placed above 2 letters representing endpoints. The arc symbol can represent the length (l) of the arc or the measurement (m) of the angle formed by the endpoints and the center of the circle. Examples:

   • lA⌒B = 7 inches (the length of arc AB is 7 inches)
   • mA⌒B = 60° (the arc AB has a measure of 60°)
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18

Radians: rad or c

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1. 
   The abbreviation rad indicates the unit of angle measurement, radians. A radian is a unit of angular measurement (like degrees), defined as the angle in a circle where the arc length equals the radius. A full circle, or 360 degrees, is equal to 2π radians (2π rad). Examples:

   • π rad = 180°
   • π/2 rad = 90°

19

Gradians: grad or g

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1. 
   The abbreviation grad indicates gradians, an outdated unit of angular measurement. You probably won’t see this very often, but it does sometimes appear in surveying and other practices. In this measurement system, a full circle is 400 gradians, and a right angle (90 degrees) is 100 gradians. This system was invented during the French Revolution to “decimalize” angle measurements, but it largely failed to catch on. Examples:

   • 360° = 400 grad
   • 90° = 100 grad
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20

Prime (Arcminute): ′

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1. 
   The arcminute symbol ′ indicates one-sixtieth of a degree. It’s a unit of measurement reserved for very small angles in geometry, as well as fields like astronomy, surveying, and map-making. There are 60 arcminutes in 1 degree (like how there are 60 minutes in one hour; hence the name, arcminute). Examples:

   • 1º = 60´
   • ∠ABC = 60º59′

21

Double Prime (Arcsecond): ″

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1. 
   The arsecond symbol ″ indicates one-sixtieth of an arcminute. When it comes to very, very, very tiny angles (like the angle between 2 very distant planets in the night sky), arseconds are used. Ana arsecond is a sixtieth of an arcminute, which is 1/3600th of 1 degree, which is 1/1,296,000th of a full circle. Examples:

   • 1′ = 60″
   • ∠DEF = 60°59′59″
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22

Therefore: ∴

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1. 
   The therefore symbol ∴ is shorthand for a conclusion from previously stated facts. If you’re doing a geometry proof, ∴ indicates the deduction drawn from the given information. It’s used to streamline arguments and provide a clear transition from premises to conclusions. Examples:

   • a = b ∴ b = a (a equals b, therefore b equals a)
   • All rectangles have four sides. ∴ All squares have four sides.

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