# Angles On One Side of A Straight Line

### Angles on one side of a straight line will always add to **180 degrees**.

If a line is split into 2 and you know one angle you can always find the other one.

30° + 150° =

**180°**

### Example: If we know one angle is 45° what is angle **"a"** ?

Angle a is 180° − 45° =
135° |

This method can be used for several angles on one side of a straight line.

### Example: What is angle **"b"** ?

Angle Sum of known angles = 45° + 39° + 24°
Angle |