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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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