Jambmaths question:
Find the curved surface area of a cone with circular base diameter 10cm and height 12cm
Option A:
25πcm2
Option B:
120πcm2
Option C:
156πcm2
Option D:
65πcm2
Jamb Maths Solution:
$\begin{align} & r=\frac{d}{2}=\frac{10}{2}cm=5cm \\ & h=12cm \\ & {{l}^{2}}={{h}^{2}}+{{r}^{2}}\text{ (pythagoras theorem }\!\!\}\!\!\text{ } \\ & {{l}^{2}}={{12}^{2}}+{{5}^{2}}=169 \\ & A=\pi rl \\ & A=\pi (13\times 5)=65\pi c{{m}^{2}} \\\end{align}$
Jamb Maths Topic:
Year of Exam: