## Right Circular Cones

right circular cone is similar to a regular pyramid except that its base is a circle. The vocabulary and equations pertaining to the right circular cone are similar to those for the regular pyramid. Refer to Figure 1 for the vocabulary regarding right circular cones. Figure 1 A right circular cone.

Theorem 96: The lateral area, LA, of a right circular cone with base circumference C and slant height l is given by the following equation. Theorem 97: The total area, TA, of a right circular cone with lateral area LA and base area B is given by the following equation. Theorem 98: The volume, V, of a right circular cone with base area B and altitude h is given by the following equation. Example 1: Figure 2 is a right circular cone; find (a) LA (b) TA and (c) V. Figure 2 Finding the lateral area, total area, and volume of a right circular cone.

(a)

The slant height, radius, and altitude of a right circular cone form a right triangle, as shown in Figure 3. Figure 3 The right triangle formed by the slant height, radius, and altitude of a right circular cone. • (b) • (c) 