A curve has parametric equations
$$x = 2\cot t, \quad y = 2\sin^2 t, \quad 0 < t \leq \frac{\pi}{2}.$$
- Find an expression for \(\frac{dy}{dx}\) in terms of the parameter \(t\). [4]
- Find an equation of the tangent to the curve at the point where \(t = \frac{\pi}{4}\). [4]
- Find a cartesian equation of the curve in the form \(y = f(x)\). State the domain on which the curve is defined. [4]