Question

The total surface area of a right circular cone of slant height 13 cm is 90π cm². Calculate: its volume in cm³. Take π = 3.14 

Answer 1

Total surface area of cone = 90π cm² 

slant height (l) = 13 cm 

Now 

h = `sqrt ("l"^2 - "r"^2)`

`= sqrt (13^2 - 5^2)`

`= sqrt (169 - 25)`

`= sqrt 144`

h = 12 cm

Volume = `1/3 pi "r"^2 "h"`

`= 1/3 xx 3.14 xx 5 xx 5 xx 12`

= 314 cm³