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If sin beta is the G.M between ...

If ` sin beta ` is the G.M between ` sin alpha ` and ` cos alpha ` , then ` cos 2 beta ` is

A

`2 sin ^2 ((pi )/(4) - alpha)`

B

`2 cos^2 ((pi)/(4) - alpha)`

C

`2 cos^2 ((pi)/(2)+alpha )`

D

`2 sin ^2 (( pi)/(2 ) + alpha )`

Text Solution

Verified by Experts

The correct Answer is:
A
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