Question

4sinx.sin(x+pi/3).sin(x+2pi/2pi3)=sin3x

Answer 1

Answer:

Substitution is method is the best when it comes to solve such problems rather than the normal conventional method,let me substitute x=0 in the above problem

L.H.S= 0

As the value of sin x =0 and as multiplication sign is in between the rest of the term doesn't matter

RHS= sin 3x=0

As L.H.S= R.H.S

Hence proved

I am assuming x=0 for ease of calculation, you can take any values that you need and the results won't change.