# Trigonometry Examples

,

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 .