Examples

Evaluate Using the Given Value
,
Step 1
Replace the variable with in the expression.
Step 2
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 3
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.
Step 4
The exact value of is .
Step 5
Multiply by .
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