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The value of sin⁡(90o−θ)cos⁡(90o−θ)cot⁡(90o−θ)cos⁡2θ−1\frac{\sin(90^o - \theta)\cos(90^o - \theta)\cot(90^o - \theta)}{\cos^2 \theta -1}cos2θ−1si
Question

The value of sin(90oθ)cos(90oθ)cot(90oθ)cos2θ1\frac{\sin(90^o - \theta)\cos(90^o - \theta)\cot(90^o - \theta)}{\cos^2 \theta -1}​ is ___________.

A.

tanθ\tan \theta​​

B.

00​​

C.

1-1​​

D.

2sinθcosθ2\sin\theta\cos\theta​​

Correct option is C

Given:

sin(90oθ)cos(90oθ)cot(90oθ)cos2θ1\frac{\sin(90^o - \theta)\cos(90^o - \theta)\cot(90^o - \theta)}{\cos^2 \theta -1}​​

Formula Used:

tanθ=sinθcosθ\tan \theta = \frac{\sin \theta}{\cos\theta}​​

sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1​​

sin(90oθ)=cosθ\sin(90^o - \theta) = \cos \theta​​

cos(90oθ)=sinθ\cos(90^o - \theta) = \sin \theta​​

cot(90oθ)=tanθ\cot(90^o - \theta) = \tan \theta​​

Solution:

sin(90oθ)cos(90oθ)cot(90oθ)cos2θ1\frac{\sin(90^o - \theta)\cos(90^o - \theta)\cot(90^o - \theta)}{\cos^2 \theta -1}​​

sinθcosθtanθcos2θ1\frac{\sin\theta\cos\theta\tan\theta}{\cos^2 \theta -1}

sinθsinθcos2θ1\frac{\sin \theta \sin \theta }{\cos^2 \theta -1}​​

sin2θcos2θ1\frac{\sin^2 \theta}{\cos^2 \theta - 1}​​

1cos2θcos2θ1\frac{1 - \cos^2 \theta}{\cos^2 \theta - 1}​​

=(cos2θ1)cos2θ1= \frac{ -(\cos^2 \theta - 1)}{\cos^2 \theta - 1}​​

= -1

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