Question

1+cos(8x)= a. 4cos(2x) b. 2sin^2(4x) C.4sin(2x) D.2cos^(4x)

Answer 1

$cos^2(x)+sin^2(x)=1 \\ 1=cos^2(4x)+sin^2(4x) \\ \\ cos(2x)=cos^2(x)-sin^2(x) \\ cos(8x)=cos(4 \times 2x)=cos^2(4x)-sin^2(4x) \\ \\ \\ 1+cos(8x)=cos^2(4x)+sin^2(4x) +cos^2(4x)-sin^2(4x) \\ cos^2(4x)+cos^2(4x)=2cos^2(4x)$

D.2cos^(4x)

Answer 2

Answer:

2Cos^2(4x)

Step-by-step explanation:

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