Question

Rewrite with only sin x and cos x.

sin 3x

Answer 1

Sum and Difference Formulas

sin(A+B)=sin A cos B + cos A sin B
sin(A-B)=sin A cos B - cos A sin B
cos(A+B)=cos A cos B - sin A sin B
cos(A-B)=cos A cos B + sin A sin B

http://www.ies.co.jp/math/java/trig/kahote/kahote.html

Answer 2

@Schrodinger spent alot of time covering this material with you yesterday. review that material.