Differential Equations Question 51

Question: Solution of the differential equation $ \sin \frac{dy}{dx}=a $ with $ y(0)=1 $ is

[Kurukshetra CEE 1998]

Options:

A) $ {{\sin }^{-1}}\frac{(y-1)}{x}=a $

B) $ \sin \frac{(y-1)}{x}=a $

C) $ \sin \frac{(1-y)}{(1+x)}=a $

D) $ \sin \frac{y}{(x+1)}=a $

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Answer:

Correct Answer: B

Solution:

Given $ \sin \frac{dy}{dx}=a $ ; $ dy={{\sin }^{-1}}adx $

Integrating both sides, $ \int _{{}}^{{}}{dy}=\int _{{}}^{{}}{{{\sin }^{-1}}adx} $

$ y=x{{\sin }^{-1}}a+c $ and $ y(0)=0+c=1 $ ,
$ \therefore c=1 $

$ \therefore y=x{{\sin }^{-1}}a+1 $

Therefore $ a=\sin \frac{y-1}{x} $ .