Reference Angles - Video Tutorials & Practice Problems
Reference Angles on the Unit Circle
Identify the reference angle of each given angle.
120°
30°
45°
60°
Identify the reference angle of each given angle.
47π rad
6π
4π
3π
Identify the reference angle of each given angle.
210°
30°
45°
60°
Trig Values in Quadrants II, III, & IV
Example 1
Identify what angle, θ , satisfies the following conditions.
sinθ=21; tanθ < 0
30°
150°
60°
300°
Identify what angle, θ , satisfies the following conditions.
cosθ=23; sinθ < 0
30°
60°
120°
330°
Identify what angle, θ , satisfies the following conditions.
tanθ=−1; cosθ > 0
45°
135°
315°
330°
Example 2
Coterminal Angles on the Unit Circle
For each expression, identify which coterminal angle to use & determine the exact value of the expression.
sin37π
21
2
23
323
For each expression, identify which coterminal angle to use & determine the exact value of the expression.
tan765°
−1
1
0
undefined
For each expression, identify which coterminal angle to use & determine the exact value of the expression.
cos(−410π)
0
1
−1
22