Question

Cos 3x + cos 5x + cos 7x +cos 15x = 4 cos 4x cos5x cos6x.​

Answer 1

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Answer 2

Answer:

Hope it helps you...

Step-by-step explanation:

In this question..

Firstly take LHS..

Then put formula of..

CosC +CosD =2cos(C+D)/2 ×cos(C-D) /2

Then we find that our RHS be coming

Then

LHS =RHS

Hence proved.

Thank you.