SSC Quantitative Aptitude Trigonometry Question Bank Trigonometry (II)

  • question_answer
    If \[\sin \,\theta +\text{cosec}\,\theta =2,\]then the value of \[{{\sin }^{7}}\theta +\text{cose}{{\text{c}}^{7}}\theta \]is

    A) 1

    B) \[\frac{1}{2}\]

    C) 2

    D) 0

    Correct Answer: C

    Solution :

    [c] \[\sin \theta +\operatorname{cosec}\theta =2\] \[\Rightarrow \]   \[\sin \theta +\frac{1}{\sin \theta }=2\] \[\Rightarrow \]   \[{{\sin }^{2}}\theta +1=2\sin \theta \] \[\Rightarrow \]   \[{{\sin }^{2}}\theta -2\sin \theta +1=0\] \[\Rightarrow \]   \[{{(sin\theta -1)}^{2}}=0\] \[\Rightarrow \]   \[\sin \theta =1=\sin 90{}^\circ \] \[\therefore \]      \[\theta =90{}^\circ \] \[\therefore \]      \[{{\sin }^{7}}\theta +\text{cose}{{\text{c}}^{7}}\theta =1+1=2\]


You need to login to perform this action.
You will be redirected in 3 sec spinner