Differentiation Question 78

Question: If $ u={{\sin }^{-1}}( \frac{y}{x} ), $ then $ \frac{\partial u}{\partial x} $ is equal to

[Tamilnadu (Engg.) 1992]

Options:

A) $ -\frac{y}{x^{2}+y^{2}} $

B) $ \frac{x}{\sqrt{1-y^{2}}} $

C) $ \frac{-y}{\sqrt{x^{2}-y^{2}}} $

D) $ \frac{-y}{x\sqrt{x^{2}-y^{2}}} $

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Answer:

Correct Answer: D

Solution:

$ u={{\sin }^{-1}}\frac{y}{x} $ ; $ \tan u $

$ \frac{\partial u}{\partial x}=\frac{1}{\sqrt{1-\frac{y^{2}}{x^{2}}}}.( -\frac{y}{x^{2}} )=-\frac{y}{x\sqrt{x^{2}-y^{2}}} $ .