Question

Cos4x=1-8sin^2 xcos^2x

Answer 1

I hope this answer help you

Answer 2

Answer:

Take cos4x as

cos2(2x)

= 1-2Sin^2

= 1 -2(sin2x)^2

= 1-2(sinx cos)^2

= 1-2 (4sin^2x cos^2x)

= 1-8 sin^2cos^2

= RHS

(OR)

RHS =1- 8 sin^2x cos^2x

= 1-4 (2sin^2x cos^2x)

= 1-4(sin2x)^2

= 1-4sin^2 2x (bcz1-2sin^2x = cosx)

= cos2(2x)

= 4cosx =LHS

hope this helps you

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