Differential Equations Question 356

Question: The solution of the differential equation $ \frac{dy}{dx}+\frac{1+\cos 2y}{1-\cos 2x}=0 $

[AISSE 1982; Karnataka CET 2004]

Options:

A) $ \tan y+\cot x=c $

B) $ \tan y\cot x=c $

C) $ \tan y-\cot x=c $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ \frac{dy}{dx}=-\frac{1+\cos 2y}{1-\cos 2x} $

Therefore $ \frac{dy}{dx}=-\frac{2{{\cos }^{2}}y}{2{{\sin }^{2}}x} $

Therefore $ {{\sec }^{2}}ydy=-cose{c^{2}}xdx $

On integrating both sides, we get $ \tan y=\cot x+c $

Therefore $ \tan y-\cot x=c $ .