The Lesson

An straight angle is an angle of 180°. A straight angle is a half of a revolution.

straight angle

Dictionary Definition

The Oxford English Dictionary defines a straight angle as "an angle of 180°."

Real Examples of Straight Angles

The angles below are all straight angles:

a straight angle of 180 degrees

What's in a Name?

A straight angle is called straight because it forms a straight line.

Do a 180

A straight angle is half a revolution, it changes the direction to point the other way.

an 180 degree turn is a reversal of direction The phrases "do a 180", "a complete 180" refers to someone who completely changes their mind or direction the other way.

Two Right Angles

A straight angle is two right angles because 180° = 2 × 90°.

2 right angles make a straight angles

Supplementary Angles

Two angles are supplementary if they add up to a straight angle.

a supplementary angle

Drag and Drop Game

Here is a drag-and-drop game to help you learn about the types of angles.