## The Lesson

An straight angle is an angle of 180°. A straight angle is a half of a revolution.## 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:## 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.The phrases "do a 180", "a complete 180" refers to someone who completely changes their mind or direction the other way.