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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

`cos 2n alpha `

B

`sin 2n alpha `

C

`cos 2alpha `

D

`sin 2 alpha `

Text Solution

Verified by Experts

The correct Answer is:
C
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