A curve has the parametric equations
x=tan2tx = \tan^2 tx=tan2t, y=costy = \cos ty=cost, where 0<t<π2\displaystyle 0 < t < \frac{\pi}{2}0<t<2π
Find an expression for dydx\displaystyle \frac{dy}{dx}dxdy in terms of ttt.
Find an equation for the tangent to the curve at the point where t=π4\displaystyle t = \frac{\pi}{4}t=4π.