JEE Main & Advanced Mathematics Differentiation Question Bank Differentiation of implicit function Parametric

  • question_answer
    If \[x=a\sin \theta \] and \[y=b\]\[\cos \theta ,\] then \[\frac{{{d}^{2}}y}{d{{x}^{2}}}\] is [UPSEAT 2002]

    A)            \[\frac{a}{{{b}^{2}}}{{\sec }^{2}}\theta \]

    B)            \[\frac{-b}{a}{{\sec }^{2}}\theta \]

    C)            \[\frac{-b}{{{a}^{2}}}{{\sec }^{3}}\theta \]

    D)            \[\frac{-b}{{{a}^{2}}}{{\sec }^{3}}\theta \]

    Correct Answer: C

    Solution :

               \[\frac{dx}{d\theta }=a\cos \theta \] and \[\frac{dy}{d\theta }=-b\sin \theta \]            Þ  \[\frac{dy}{dx}=\frac{-b}{a}\tan \theta \] and \[\frac{{{d}^{2}}y}{d{{x}^{2}}}=\frac{-b}{a}{{\sec }^{2}}\theta \frac{d\theta }{dx}\]                    Þ  \[\frac{{{d}^{2}}y}{d{{x}^{2}}}=\frac{-b}{a}{{\sec }^{2}}\theta \frac{1}{a\cos \theta }=\frac{-b}{{{a}^{2}}}{{\sec }^{3}}\theta \].


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