Question

Prove that cos theta cos π/3+theta cos π/3-theta =cos 3 theta

Answer 1

Answer:

I hope it will help you

Step-by-step explanation:

Apply the trig identity:

cosa+cosb=2cos(a+b2).cos(a−b2)

Sum S=cos(π3+x)+cos(π3−x)=2cos(π3).cosx

Trig table gives --> cos(π3)=12. Therefor,

S = cos x