Coterminal and Reference Angles

Front

What is a reference angle?

Back

A reference angle is the acute angle formed by the terminal side of an angle and the x-axis, always measured as a positive angle.

Front

How do you find the reference angle for an angle in standard position?

Back

To find the reference angle, subtract the angle from 180° if it is in the second quadrant, subtract 180° from the angle if it is in the third quadrant, or subtract the angle from 360° if it is in the fourth quadrant.

Front

What is the reference angle for 240°?

Back

60°

Front

How do you find the reference angle for a negative angle?

Back

First, convert the negative angle to a positive angle by adding 360° until it is positive, then find the reference angle using the same rules as for positive angles.

Front

What is the reference angle for -310°?

Back

50°

Front

What is the reference angle for -30°?

Back

30°

Front

What are coterminal angles?

Back

Coterminal angles are angles that share the same terminal side when drawn in standard position, differing by full rotations of 360°.

Front

How do you find a coterminal angle for a given angle?

Back

To find a coterminal angle, add or subtract 360° from the given angle until you reach the desired angle.

Front

What are the negative and positive coterminal angles of -225°?

Back

135° (positive coterminal) and -585° (negative coterminal).

Front

Find a coterminal angle to 5°.

Back

365°.