BCECE Engineering BCECE Engineering Solved Paper-2005

  • question_answer
    The value of \[\sin {{600}^{o}}\,\cos {{330}^{o}}+\cos {{120}^{o}}\sin {{150}^{o}}\]is:

    A)  1                            

    B)         \[-1\]                    

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

    D)         \[\frac{1}{\sqrt{2}}\]

    Correct Answer: B

    Solution :

    \[\sin {{600}^{o}}\cos {{330}^{o}}+\cos {{120}^{o}}\sin {{150}^{o}}\] \[=\sin ({{720}^{o}}-{{120}^{o}})\cos ({{180}^{o}}+{{150}^{o}})\]                                                 \[+\cos {{120}^{o}}\sin {{150}^{o}}\] \[=\sin {{120}^{o}}\cos {{150}^{o}}+\cos {{120}^{o}}\sin {{150}^{o}}\] \[=\sin ({{120}^{o}}+{{150}^{o}})\] \[=\sin {{270}^{o}}=\sin ({{180}^{o}}+{{90}^{o}})\] \[=-\sin {{90}^{o}}=-1\]


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