Question

Find out the curved surface area of a right circular cone having slant height

21m and diameter of base=24m.​

Answer 1

Given :

• Slant height of right circular cone = 21m
• Diameter of base of right circular cone = 24m

To find :

Curved surface area of right circular cone.

Formula used :

1. Radius = Diameter ÷ 2
2. CSA of right circular cone = πrl

Here ,

• r = radius of base of right circular cone
• l = slant height of right circular cone
• π = (22/7)

Solution :

First of all we need to find out Radius of base of right circular cone.

Radius = Diameter ÷ 2

Radius = 24m ÷ 2

Radius = 12m

$\sf \implies\:CSA \:=\:\pi \times 21m \times 12m$

$\sf \implies\:CSA \:=\: \dfrac{22}{7} \times 21 \times 12 {m}^{2}$

$\sf \implies\:CSA \:=\: \dfrac{21}{7} \times( 22 \times 12) {m}^{2}$

$\sf \implies\:CSA \:=\: 3 \times 264 {m}^{2}$

$\sf \implies\:CSA \:=\: 792 {m}^{2}$

ANSWER : 792 m²