Mathematics for Teaching Calculus Differentiation problem in parametric context with solution

Differentiation problem in parametric context with solution

This is hot off the press-a question taken from the recently concluded 2011 September Preliminary Examinations of a school in Singapore. It deals with applications of differentiation in the parametric context. Extensive trigonometry is employed here together with the manipulation of surd forms. I have personally worked out everything for your (the student’s) reference.

If you want a real calculus challenge, the problem below should satisfy your appetite. Peace.


The parametric equations of a curve  are

x = sin2t and y= a cos t

where is a positive constant \frac{-\pi}{2} \le t \le\frac{\pi}{2}

(i) Find the equation of the tangent to the curve at the point P  where t= \frac{\pi}{4}.

(ii) The normal to the curve at the point Q where t = \frac {\pi}{3} intersects the axis at R. Find the coordinates of R and hence show that the area enclosed by the normal at Q , the tangent P and the x-axis is



Frederick Koh is a teacher residing in Singapore who specialises in teaching the A level maths curriculum. He has accumulated more than a decade of tutoring experience and loves to share his passion for mathematics on his personal site

Mr Koh is also the author of the post Working with summation.

I have created a GeoGebra applet to visualize Question 1 above.


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