Trigonometry
Determine the exact value of the following trigonometric function without using a calculator.
cos165°\cos165\degreecos165°
6−24\frac{\sqrt6-\sqrt2}{4}46−2
6+24\frac{\sqrt6+\sqrt2}{4}46+2
2−64\frac{\sqrt2-\sqrt6}{4}42−6
−2−64\frac{-\sqrt2-\sqrt6}{4}4−2−6