Symbols in Geometry
Common Symbols Used in Geometry
Symbols save time and space when writing. Here are the most common geometrical symbols:
Symbol | Meaning | Example | In Words |
---|---|---|---|
△ | Triangle | △ABC has 3 equal sides | Triangle ABC has three equal sides |
∠ | Angle | ∠ABC is 45° | The angle formed by ABC is 45 degrees. |
⊥ | Perpendicular | AB⊥CD | The line AB is perpendicular to line CD |
∥ | Parallel | EF∥GH | The line EF is parallel to line GH |
° | Degrees | 360° | 360 degrees (a full rotation!) |
∟ | Right Angle (90°) | ∟ is 90° | A right angle is 90 degrees |
Line Segment "AB" | AB | The line segment between A and B | |
Line "AB" | The infinite line that includes A and B | ||
Ray "AB" | The line that starts at A, goes through B and continues on | ||
≅ | Congruent (same shape and size) | △ABC ≅ △DEF |
Triangle ABC is congruent to triangle DEF |
∼ | Similar (same shape, different size) | △DEF∼△MNO | Triangle DEF is similar to triangle MNO |
∴ | Therefore | a=b b=a | a equals b, therefore b equals a |
Example: In △ABC, ∠BAC is ∟
Is really saying: "In triangle ABC, the angle BAC is a right angle"
Naming Angles
For angles the central letter is where the angle is.
Example: ∠ABC is 45°
The point "B" is where the angle is.
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