How do you prove that $-cot2x = (sec^2x-2)/(2tanx$ ?

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Answer 1 · 2018-04-16T10:31:38

Please refer to a Proof in the Explanation.

Knowing that, $tan2x=(2tanx)/(1-tan^2x)$ , we have,

$-cot2x=-1/(tan2x)=(tan^2x-1)/(2tanx)={(sec^2x-1)-1}/(2tanx)$ .

$rArr -cot2x=(sec^2x-2)/(2tanx)$ .

How do you prove that -cot2x = (sec^2x-2)/(2tanx -cot2x = (sec^2x-2)/(2tanx ?