Symbols in Geometry

Common Symbols Used in Geometry

Symbols save time and space when writing. Here are the most common geometrical symbols:

SymbolMeaningExampleIn Words Triangle ABC has 3 equal sidesTriangle ABC has three equal sides Angle ABC is 45° The angle formed by ABC is 45 degrees. PerpendicularAB CD The line AB is perpendicular to line CD ParallelEF GH The line EF is parallel to line GH Degrees360°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 Thereforea=b b=aa 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.