The height and the slant height of a cone are 21 cm and 28 cm, respectively. Find the volume of the cone.
Volume of the cone =13πr2h
Given
Slant height=l=28cm
Height of cone =h=21cm
Let radius of cone =rcm
We know that
l2=h2+r2
282=212+r2
⇒282−212=r2
⇒r2=√7.49
⇒r=7√7cm
So,
Volume of cone =13πr2h
=13⋅227⋅7√7⋅7√7⋅21cm3
=22⋅7√7⋅7√7cm3
=22.7.7.(√7)2cm3
=22.7.7.7cm3
=7546cm3
∴ Volume of cone =7546cm3.