JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Self Evaluation Test - Trigonometric Function

  • question_answer
    The difference of two angles is \[1{}^\circ ;\] the circular measure of their sum is 1. What is the smaller angle in circular measure?

    A) \[\left[ \frac{180}{\pi }-1 \right]\] 

    B) \[\left[ 1-\frac{\pi }{180} \right]\]

    C) \[\frac{1}{2}\left[ 1-\frac{\pi }{180} \right]\]        

    D) \[\frac{1}{2}\left[ \frac{180}{\pi }-1 \right]\]

    Correct Answer: C

    Solution :

    Let the angles are \[\alpha \]and \[\beta ,\] then \[\alpha -\beta =1{}^\circ \] \[\Rightarrow \,\,\alpha -\beta =\frac{\pi }{180{}^\circ }\] is circular measure .. .(i) As given,   \[\alpha +\beta =1\]                 ...(ii) On solving Eqs. (i) and (ii), we get, \[\alpha =\frac{1}{2}\left[ 1+\frac{\pi }{180{}^\circ } \right]\] and \[\beta =\frac{1}{2}\left[ 1-\frac{\pi }{180{}^\circ } \right]\] \[\beta \] is the smaller angle. Hence, smaller angle \[=\frac{1}{2}\left[ 1-\frac{\pi }{180{}^\circ } \right]\]


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