10th Class Mathematics Introduction to Trigonometry Question Bank MCQs - Introduction to Trigonometry

  • question_answer
    Evaluate:  \[\sqrt{\frac{\sec \theta -1}{\sec \theta +1}}+\sqrt{\frac{\sec \theta +1}{\sec \theta -1}}\]

    A) \[2\sin \theta \]

    B) \[2\cos \theta \]

    C) \[2\text{cosec}\theta \]

    D) \[2\text{sec }\theta \]

    Correct Answer: C

    Solution :

    [c] We have,  \[\sqrt{\frac{\sec \theta -1}{\sec \theta +1}}+\sqrt{\frac{\sec \theta +1}{\sec \theta -1}}\]
    \[=\frac{(\sec \theta -1)+(\sec \theta +1)}{{}}=\frac{2\sec \theta }{{}}\] \[[{{\sec }^{2}}\theta -1={{\tan }^{2}}\theta ]\]
    \[=\frac{2\sec \theta }{\tan \theta }=\frac{2}{\cos \theta }\times \frac{\cos \theta }{\sin \theta }=\frac{2}{\sin \theta }=2\cos ec\,\,\theta \]


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