Question

Prove that sin 2x =2sinx . cos x . For any angle x

Answer 1

Heya,

Now, for two angles A and B we have
sin (A+B) = sin A cos B+ cos A sin B

Now, if A=B=x, then,
sin (x+x) = sin x cos x+ cos x sin x
or, sin 2x = 2 sin x cos x (PROVED)