Differential Equations

Let y = y(x) be a solution curve of the differential equation \((y + 1){\tan ^2}x\,dx + \tan x\,dy + y\,dx = 0\), \(x \in \left( {0,{\pi \over 2}} \right)\). If \(\mathop {\lim }\limits_{x \to 0 + } xy(x) = 1\), then the value of \(y\left( {{\pi \over 4}} \right)\) is :