Question

Find the curved surface area of a right circular cone whose height is 15 cm and base radius is 8 cm. `["Use"  pi = 22/7]`

Answer 1

Curved surface area (CSA) = πrl

where, 

r = radius of the base,

l = slant height of the cone,

π = `22/7`

The slant height l is given by the Pythagoras theorem:

`l = sqrt(r^2 + h^2)`

r = 8cm and h = 15 cm

`l = sqrt(8^2 + 15^2)`

= `sqrt(64 + 225)`

= `sqrt289`

= 17 cm

Calculate the Curved Surface Area using the formula: 

CSA = πrl

CSA = `22/7 xx 8 xx 17`

CSA = `(22 xx 8 xx 17)/7`

= `2992/7`

CSA = 427.43 cm² (approximately)