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Question

Question: cos (tan<sup>–1</sup> x) =\]...

cos (tan–1 x) =]

A

1+x2\sqrt{1 + x^{2}}

B

11+x2\frac{1}{\sqrt{1 + x^{2}}}

C

1 + x2

D

None of these

Answer

11+x2\frac{1}{\sqrt{1 + x^{2}}}

Explanation

Solution

Let q = tan–1 x ̃ x = tan q

\ cos q = 1/1+tan2θ\sqrt{1 + \tan^{2}\theta}= 1/1+x2\sqrt{1 + x^{2}} = cos (tan–1 x)