Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-21

  • question_answer
    \[\sqrt{\frac{1-\sin A}{1+\sin A}}\]is equal to

    A) \[\cos A-\tan A\] 

    B) \[\cos A-\cot A\]

    C) \[\sec A-\cot A\] 

    D) \[\sec A-\tan A\]

    Correct Answer: D

    Solution :

    Given expression\[=\frac{\sqrt{1-\sin A}}{\sqrt{1+\sin A}}\times \frac{\sqrt{1-\sin A}}{\sqrt{1-\sin A}}\] \[\,=\frac{(1-\sin A)}{\sqrt{1-{{\sin }^{2}}A}}\] \[=\frac{(1-\sin A)}{\sqrt{{{\cos }^{2}}}A}=\frac{(1-\sin A)}{\cos A}\] \[=\left( \frac{1}{\cos A}-\frac{\sin A}{\cos A} \right)\] \[=\sec A-\tan A\]


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