J & K CET Engineering J and K - CET Engineering Solved Paper-2012

  • question_answer
    If \[\sin x\,\cos \,y=\frac{1}{4}\]and \[3\tan x=4\tan y,\], then \[\sin (x-y)\] equals to

    A)  \[\frac{1}{16}\]

    B)  \[\frac{1}{8}\]

    C)  \[\frac{3}{16}\]

    D)  \[\frac{3}{4}\]

    Correct Answer: A

    Solution :

    Given,  \[\sin x\cos y=\frac{1}{4}\] and \[3\tan x=4\tan y\] \[\therefore \] \[\frac{3\,\sin \,x}{\cos x}=\frac{4\sin y}{\cos y}\] \[\Rightarrow \] \[3\sin x\cos y=4\sin y\cos x\] \[\Rightarrow \] \[3\times \frac{1}{4}=4\sin y\cos x\] \[\Rightarrow \] \[\sin y\cos x=\frac{3}{16}\] \[\therefore \] \[\sin (x-y)=\sin x\cos y-\cos x\sin y\] \[=\frac{1}{4}-\frac{3}{16}\] \[=\frac{1}{16}\]


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