Question

If it is required to make a hollow cone 24 cm high whose base radius is 7 cm. Find the area of the sheet metal required including the base. Also, find the capacity of this cone. [3 MARKS]

Answer 1

Formula: 1 Mark
Application: 1 Mark
Answer: 1 Mark

Given $\therefore h=24cm,r=7cml=\sqrt{r^2+h^2}=\sqrt{7^2+{24}^2}=\sqrt{49+576}=\sqrt{625}=25cm$
$\therefore$ Area of sheet required $=\pi r^2+\pi rl=\pi r(r+1)=\frac{22}{7}\times 7\times (7+25)=22\times 32=704c{m}^2$
$\therefore$ Volume of cone $=\frac{1}{3}\pi r^{2}h=\frac{1}{3}\times \frac{22}{7}\times 7\times \times 24=1232c{m}^3$