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If f(x) = cos x\ cos 2x\ cos 2^2\ x\ cos...

If `f(x) = cos x\ cos 2x\ cos 2^2\ x\ cos 2^3 x\ ....cos2^(n-1) x` and `n gt 1,` then `f'(pi/2)` is

A

1

B

0

C

-1

D

None of these

Text Solution

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The correct Answer is:
A
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