Question

Proof that cos2x-sin2x=cosx-sinx.

Answer 1

Answer:

This is not true.

Step-by-step explanation:

Let say x=Pi/4.

On the left side we have: cos 2*Pi/4 - sin 2*Pi/4 = cos Pi/2 - sin Pi/2 =0 - 1 = -1

On the right side we have: cos Pi/4 - sin Pi/4 = sqrt (2)/2 - sqrt (2)/2 = 0