Question

A heap of paddy is in the form of a cone whose diameter is $4.3m$ and height is $2.8m$. If the heap is to be covered exactly by a canvas to protect it from rain, then find the area of the canvas needed.

• A. $23.1m^2$
• B. $22.1m^2$
• C. $28.1m^2$
• D. None of these

Answer 1

The correct option is A $23.1m^2$

We have,

$d=4.3m$

$r=2.15m$

$h=2.8m$

We know that the slant height of the cone

$l=\sqrt{r^2+h^2}$

So,

$l=\sqrt{{2.15}^2+{2.8}^2}$

$l=\sqrt{4.62+7.84}$

$l=\sqrt{12.46}=3.5m$

We know that the curved surface area of the cone

$=\pi rl$

So, needed canvas to protect it from rain should be equal to curved surface area

$=\pi \times 2.15\times 3.5$

$=\pi \times 7.525$

$=23.1m^2$

Hence, this is the answer