1+ cos 2x+ cos4x + cos 6x=............. ...

`1+ cos 2x+ cos4x + cos 6x=`............. A) `2 cos x cos 2x cos 3x`
B) `4 sin x cos 2x cos 3x` C) `4 cos x cos 2x cos 3x` D) `2 sin x cos 2x cos 3x`

A

`2 cos x cos 2x cos 3x`

B

`4 sin x cos 2x cos 3x`

C

`4 cos x cos 2x cos 3x`

D

`2 sin x cos 2x cos 3x`

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The correct Answer is:

C

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