# 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 ABCD The line AB is perpendicular to line CD
Parallel EFGH The line EF is parallel to line GH
Degrees 360° makes a full circle
Right Angle (90°) is 90° A right angle is 90 degrees
Line Segment "AB" AB The line 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) DEFMNO Triangle DEF is similar to triangle MNO
Therefore a=b b=a a equals b, therefore b equals a

### Example:

When someone writes: In ABC, BAC is

They are 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:

when you see "ABC is 45°", then the point "B" is where the angle is.