SSC Sample Paper SSC-CGL TIER - I Sample Test Paper-7

  • question_answer
    If \[sin\theta ~-\text{ }cos\theta ~=0,\]then. \[Si{{n}^{4}}~\theta +\text{ }co{{s}^{4}}\theta \]is equal to-

    A) 1                     

    B) \[\frac{3}{4}\]

    C) \[\frac{1}{2}\]              

    D) \[\frac{1}{4}\]

    Correct Answer: C

    Solution :

    \[\therefore sin\theta ~-cos\theta ~=0~\therefore sin\theta ~=cos\theta \] Since, \[sin\theta \]and \[cos\theta ~\] are equal for \[\theta \] = 45° So, \[si{{n}^{4}}\theta ~+co{{s}^{4}}\theta ~={{\left( sin\text{ }45{}^\circ  \right)}^{4}}+{{\left( cos\text{ }45{}^\circ  \right)}^{4}}\] =         \[{{\left( \frac{1}{\sqrt{2}} \right)}^{4}}+{{\left( \frac{1}{\sqrt{2}} \right)}^{4}}\] =         \[\frac{1}{4}+\frac{1}{4}=\frac{1+1}{4}=\frac{2}{4}=\frac{\mathbf{1}}{\mathbf{2}}\]


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