Manipal Engineering Manipal Engineering Solved Paper-2008

  • question_answer
    If\[y=\left| \cos x \right|+\left| \sin x \right|\], then\[\frac{dy}{dx}\]at\[x=\frac{2\pi }{3}\]is

    A)  0                                            

    B)  1

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

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

    Correct Answer: D

    Solution :

    In the neighborhood for\[x=\frac{2\pi }{3}\], we have \[\cos x<0\]and\[\sin x>0\] \[\therefore \]  \[y=-\cos x+\sin x\] \[\Rightarrow \]               \[\frac{dy}{dx}=\sin x+\cos x\] \[\Rightarrow {{\left( \frac{dy}{dx} \right)}_{\left( x=\frac{2\pi }{3} \right)}}=\sin \frac{2\pi }{3}+\cos \frac{2\pi }{3}\]                 \[=\frac{\sqrt{3}-1}{2}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner