JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Trigonometrical ratios of sum and difference of two and three angles

  • question_answer
    \[\sin 75{}^\circ =\]        [MNR 1979]

    A) \[\frac{2-\sqrt{3}}{2}\]

    B) \[\frac{\sqrt{3}+1}{2\sqrt{2}}\]

    C) \[\frac{\sqrt{3}-1}{-2\sqrt{2}}\]

    D) \[\frac{\sqrt{3}-1}{2\sqrt{2}}\]

    Correct Answer: B

    Solution :

    \[\sin \,{{75}^{o}}=\sin \,\,({{90}^{o}}-{{15}^{o}})=\cos \,{{15}^{o}}=\cos \,\,({{45}^{o}}-{{30}^{o}})\] \[=\frac{\sqrt{3}+1}{2\sqrt{2}}\].


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