2019 TMJC Promo Q9

2019 TMJC Promo Q9

12 marks
Promo
  1. [It is given that the volume of a cylinder of radius \(r\) and height \(h\) is \(\pi {{r}^{2}}h\).]
    List item image
    The diagram above shows a cylinder of radius \(r\) cm and height \(h\) cm inscribed in a spherical container with fixed radius \(5\)cm.
    1. Show that the volume, \(V\)cm\(^{3}\), of the cylinder is given by \(V=2\pi {{r}^{2}}\sqrt{25-{{r}^{2}}}\).[2]
    2. As \(r\) varies, use differentiation to find the exact value of \(r\) that gives a maximum \(V\) of the cylinder. Hence find the exact maximum value of \(V\), showing that this value is a maximum.[6]
  2. List item image
    The diagram shows the graph \(y=\mathrm{f}(x)\), which is strictly decreasing on the interval \((-2,1)\). Given that \(\mathrm{g}(x)=\frac{1}{2}\sin [2\mathrm{f}(x)]\), where \(-2 < x < 1\), use differentiation to determine the number of stationary points on the graph of \(y=\mathrm{g}(x)\).[4]

Video Solution:

Video Solution

Video solution locked

A free account saves your progress; this video needs a course plan.

Solution:

Solution locked

680+ questions here come with free worked solutions. A free account saves your questions and progress; this one needs a course plan.

Answer:\(\dfrac{500\sqrt{3}\,\pi}{9}\) cm³; one stationary point

Need help? Join our JC Math tuition classes.

Learn more