Mathematics 9709 · AS & A Level · Differentiation

Differentiation — practice question

The diagram depicts the curve defined by the parametric equations $x = \sin t + \cos t$, $y = \sin^3 t + \cos^3 t$, for $\frac{\pi}{4} < t < \frac{5\pi}{4}$.
(i)[3]

Show that $\frac{dy}{dx} = -3\sin t\cos t$.

(ii)[2]

Find the gradient of the curve at the origin.

(iii)[4]

Find the values of $t$ for which the curve has gradient 1, giving your answers correct to 2 significant figures.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Differentiate $y$ to give $3\sin^2 t\cos t-3\cos^2 t\sin t$

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI