Question

$\cos(2 \tan^{ - 1} ( \frac{1}{2} ) )$
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Answer 1

Answer:

Correct option is

C

±31

cos(2tan−1x)=21

∴2tan−1x=cos−1(21)

∴2tan−1x=±3π

∴tan−1x=±6π

∴x=±tan(6π)

∴x=±31

Hence, the answer is option (C).