SURFACE AREAS AND VOLUMES 259
- Given a right circular cone, which is sliced through by a plane parallel to its base, when
the smaller conical portion is removed, the resulting solid is called a Frustum of a Right
Circular Cone.
- The formulae involving the frustum of a cone are:
(i) Volume of a frustum of a cone = 121222 ✁
1
3
✂hrrrr✄ ✄.
(ii) Curved surface area of a frustum of a cone = ☎l(r 1 + r 2 ) where l = hrr^2 ✞✆ 12 ✟ ✝^2.
(iii) Total surface area of frustum of a cone = ☎l(r 1 + r 2 ) + ☎(r 12 + r^22 ) where
h = vertical height of the frustum, l = slant height of the frustum
r 1 and r 2 are radii of the two bases (ends) of the frustum.
