If $x^{2} y^{2}=\sin ^{-1} \sqrt{x^{2}+y^{2}}+\cos ^{-1} \sqrt{x^{2}+y^{2}}$, then $\frac{d y}{d x}=$

If $x^{2} y^{2}=\sin ^{-1} \sqrt{x^{2}+y^{2}}+\cos ^{-1} \sqrt{x^{2}+y^{2}}$, then $\frac{d y}{d x}=$
  1. $\frac{-y}{x}$
  2. $\frac{x}{y}$
  3. $\frac{y}{x}$
  4. $\frac{-x}{y}$

Solution

We know, $\sin ^{-1} \theta+\cos ^{-1} \theta=\frac{\pi}{2} \Rightarrow x^{2} y^{2}=\frac{\pi}{2}$ Differentiating w.r.t. $\mathrm{x}$ $\begin{array}{l} x^{2} \cdot 2 y \frac{d y}{d x}+y^{2} \cdot 2 x=0 \Rightarrow x^{2} \cdot 2 y \frac{d y}{d x}=-y^{2} \cdot 2 x \\ \frac{d y}{d x}=\frac{-y^{2} \cdot 2 x}{x^{2} \cdot 2 y}=\frac{-y}{x} \end{array}$

Asked in: MHT CET 2020 (19 Oct Shift 2)

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