SSC Quantitative Aptitude Trigonometry Question Bank Trigonometry (I)

  • question_answer
    \[\frac{\sin A}{1+\cos \,A}+\frac{\sin A}{1-\cos A}\]is \[(0{}^\circ <A<90{}^\circ )\]

    A) \[2\,\text{cosec}\,A\]

    B) \[2\sec A\]

    C) \[2\,\sin A\]

    D) \[2\cos A\]

    Correct Answer: A

    Solution :

    [a] \[\frac{\sin A}{1+\cos A}+\frac{\sin A}{1-\cos A}\] \[=\frac{\sin A\,(1-\cos A)+\sin A\,(1+\cos A)}{(1+cos\,A)(1-cos\,A)}\] \[\sin A-\sin Acos\,A+\sin A\] \[=\frac{+\sin A\cos A}{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,1-{{\cos }^{2}}A}\] \[=\frac{2\sin A}{{{\sin }^{2}}A}=2\text{cosec}\,A\]


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