 # Evaluating Trigonometric Functions at Important Angles

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In this lesson we will look at how to use the unit circle and reference angles to find some values for different trigonometric functions.

Evaluating Trigonometric Functions at Important Angles, Ex 1
How to use the unit circle and reference angles to find some values for different trig functions?
Examples:
Evaluate:
(a) sin(π/6)
(b) tan(-5π/3)
(c) cos(π/4)
(d) sec(π4)
(e) sin2(π/6) + cos2(π/4) + tan2(-5π/3)
Evaluating Trigonometric Functions at Important Angles, Ex 2
Examples:
Evaluate:
(a) cos(45°)
(b) sin (150°)
(c) tan (225°)
(d) csc (150°)

Evaluating Trigonometric Functions Using the Reference Angle, Example 1
This video reviews the unit circle in quadrant 1 and discusses how to use the reference angle to evaluate some trig functions.
The reference angle is the angle formed by the terminal ray of the original angle and the x-axis.
Examples:
Evaluate:
(a) cos (210°)
(b) tan (-45°)
Evaluating Trigonometric Functions Using the Reference Angle, Example 2
This video discusses how to use the reference angle to evaluate some more trig functions.
Evaluate
(c) sec(-π/3)
(d) csc(7π/6)

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