Mathematics

Problem

Let the function

y = f(x)

satisfy the differential equation

\frac{dy}{dx} = y \tan x - y^2 \sec x

with condition

y(0) = 1

then

y\left(\frac{\pi}{4}\right)

is equal to - (A)

\frac{1}{2}

(B)

\frac{1}{\sqrt{2}}