Differential Equations Question 39

Question: The solution of differential equation $ dy-\sin x\sin ydx=0 $ is

[MP PET 1996]

Options:

A) $ {e^{\cos x}}\tan \frac{y}{2}=c $

B) $ {e^{\cos x}}\tan y=c $

C) $ \cos x\tan y=c $

D) $ \cos x\sin y=c $

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Answer:

Correct Answer: A

Solution:

$ \int _{{}}^{{}}{\frac{dy}{\sin y}}=\int _{{}}^{{}}{\sin xdx} $

Therefore $ \log \tan \frac{y}{2}=-\cos x+c $

Therefore $ \tan \frac{y}{2}={e^{-\cos x+c}} $

Therefore $ {e^{\cos x}}\tan \frac{y}{2}=e^{C}=c $ .