Write each expression as the sine of an angle.

\f14. Use the fact that cos($ -x) = sin(x) (shown in examples), to show that sin ($ - x) = cos(x). 15. Prove that cos(x - y) + cos(x +y) = 2cos(x) cos(y).Find the exact value for each tangent expression. 1. tan 2. tan 12 3. tan -1650