Question

Prove that cos(2x)=cos(x)(4cos²(x)-3)

Answer 1

Hi Buddy

RHS===> cos(x)(4cos²(x)-3)= 4cos³x-3cosx= cos3x

LHS===> cos2x

Let x=0, => LHS, cos(2×0)= cos0= 1

=> RHS, cos(3×0)=cos0=1

Hence proved that, LHS=RHS

BYE BUDDY

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