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What Is a Straight Angle? (Mathematics Lesson)

What Is a Straight Angle?

An straight angle is an angle of 180°.

Real Examples of Straight Angles

The angles below are all straight angles:



Supplementary Angles

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



Read more about supplementary angles

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Note
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.

TWO RIGHT ANGLES

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



OTHER TYPES OF ANGLES

Straight angles are one type of angle, the other types are acute, right, obtuse, reflex and straight.