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cos(n+1) alpha * cos(n-1)alpha + sin (n+...

`cos(n+1) alpha * cos(n-1)alpha + sin (n+1)alpha * sin (n-1) alpha = `

A

`Cos2n alpha`

B

`Sin 2n alpha`

C

`Cos 2 alpha`

D

`Sin 2 alpha`

Text Solution

Verified by Experts

The correct Answer is:
C
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