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

  • question_answer
    The value of \[\sin 600{}^\circ \cos 330{}^\circ +\cos 120{}^\circ \sin 150{}^\circ \] is  [MP PET 1994]

    A) -1

    B) 1

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

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

    Correct Answer: A

    Solution :

    \[\sin \,{{600}^{o}}\,\cos \,{{330}^{o}}+\cos \,{{120}^{o}}\,\sin \,{{150}^{o}}\] \[=-\sin \,{{60}^{o}}\,\cos \,{{30}^{o}}-\sin \,{{30}^{o}}\,\cos \,{{60}^{o}}\] \[=-\left\{ \sin \,({{60}^{o}}+{{30}^{o}}) \right\}=-1\].


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