prove the identity:
1) sin4x = 2sin2xcos2x
2)cos6x = 2cos^2 3x-1
3)sin3x = sin x(4cos^2 x-1)
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1)We can prove the identity using the formula ,sin(2A)=2sinAcosA
We have the double angle formula for cos 2A
On comparing here A=3x
It can be written as
Using the sum of angle formula for sin(A+B)=sinAcosB+cosBsinA
Factoring out sinx
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