12th Class Mathematics Sample Paper Mathematics Sample Paper-5

  • question_answer
    If \[y={{\sin }^{-1}}[\sqrt{x}\sqrt{1-{{x}^{2}}}-x\sqrt{1-x}),\] then find \[\frac{dy}{dx}.\]

    Answer:

    Given express can be written as                              \[y={{\sin }^{-1}}[\sqrt{x}\sqrt{1-{{x}^{2}}}-x\sqrt{1-(\sqrt{{{x}^{2}}})}]\]       Now, put \[x=\sin \theta \] and \[x=\sin \phi \] Then, the given expression reduces to  \[y={{\sin }^{-1}}[sin\phi \sqrt{1-{{\sin }^{2}}\theta }-\sin \theta \sqrt{1-{{\sin }^{2}}\phi ]}\] \[={{\sin }^{-1}}[sin\phi cos\theta -cos\phi sin\theta ]\]             \[[\because 1-{{\sin }^{2}}A={{\cos }^{2}}A]\] \[={{\sin }^{-1}}[sin(\phi -\theta )]\]                                      \[[\because \sin A\cos B-\cos A\sin B=\sin (A-B)]\] \[=\phi -\theta ={{\sin }^{-1}}\sqrt{x}-{{\sin }^{-1}}x\]   \[[\because \,\,x=\sin \theta \,\,\,\Rightarrow \,\,\,\theta ={{\sin }^{-1}}x\] and \[\sqrt{x}=sin\phi \,\,\,\Rightarrow \,\,\,\phi =si{{n}^{-1}}\sqrt{x}]\] \[\therefore \] \[\frac{dy}{dx}=\frac{1}{\sqrt{1-{{(\sqrt{x})}^{2}}}}\cdot \frac{1}{2\sqrt{x}}-\frac{1}{\sqrt{1-{{x}^{2}}}}\]             \[=\frac{1}{2\sqrt{x}\sqrt{1-x}}-\frac{1}{\sqrt{1-{{x}^{2}}}}\]


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