A function $y=f(x)$ satisfies $f(x) \sin 2 x+\sin x-\left(1+\cos ^2 x\right) f^{\prime}(x)=0$ with condition $f(0)=0$. Then, $f\left(\frac{\pi}{2}\right)$ is equal to
Solution
<p>$$\begin{aligned}
& \frac{d y}{d x}-\left(\frac{\sin 2 x}{1+\cos ^2 x}\right) y=\sin x \\
& \text { I.F. }=1+\cos ^2 x \\
& y \cdot\left(1+\cos ^2 x\right)=\int(\sin x) d x \\
& =-\cos x+C \\
& x=0, C=1 \\
& y\left(\frac{\pi}{2}\right)=1
\end{aligned}$$</p>
About this question
Subject: Mathematics · Chapter: Differential Equations · Topic: Order and Degree
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