10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
    Find the value of, \[\sqrt{\frac{1+\cos \theta }{1-\cos \theta }}+\sqrt{\frac{1-\cos \theta }{1+\cos \theta }}\]

    A)  \[2\sec \theta \]             

    B)  \[\sec \theta \]

    C)  \[2co\sec \theta \]          

    D)  None of these

    Correct Answer: C

    Solution :

    (c): \[\sqrt{\frac{(1+cos\,\theta )(1+cos\,\theta )}{(1-cos\,\theta )(1+cos\,\theta )}}+\sqrt{\frac{(1-cos\,\theta )(1-cos\,\theta )}{(1+\cos \,\theta )(1-cos\theta )}}\] \[=\sqrt{\frac{{{(1+cos\,\theta )}^{2}}}{1-{{\cos }^{2}}\theta }}+\sqrt{\frac{{{(1-cos\theta )}^{2}}}{1-{{\cos }^{2}}\theta }}\] \[=\frac{1+\cos \theta }{\sin \theta }+\frac{1-\cos \theta }{\sin \theta }=\frac{1+\cos \theta +1-\cos \theta }{\sin \theta }\] \[=\frac{2}{\sin \theta }=2\,\,\cos ec\theta \]        


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