Find the equation of the curve passing through the point `(0,pi/4)` whose differential equation is `sinx" "cosy" "dx" "+" "cosx" "siny" "dy" "=" "0` .

Explanation

``
\begin{aligned}
&\sin x \cos y d x+\cos x \sin y d y=0 \\

&\Rightarrow \cos x \sin y d y=-\sin x \cos y d x \\

&\Rightarrow \frac{\sin y}{\cos y} d y=\frac{-\sin x}{\cos x} d x
\end{aligned}

``
Integrate both sides,

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