11 4 Surface Area of Pyramids and Cones

11 -4 Surface Area of Pyramids and Cones Objectives: • To find the lateral area and surface area of a regular pyramid. • To find the lateral area and surface area of a right circular cone.

Vocabulary • • Vertex (also known as the apex) Regular Pyramid Slant Height Axis

Vocabulary vertex • All the faces except the base intersect at a point called the vertex (also known as the apex).

Vocabulary • If the base of a pyramid is a regular polygon and the vertex is directly over the center of the base then it is called a regular pyramid. All the lateral faces are congruent in a regular pyramid. vertex

Vocabulary vertex • The height of each lateral face is called the slant height.

Vocabulary • The axis of a cone is a segment from the vertex to the center of the circular base.

Lateral Area of a Regular Pyramid • If a regular has a lateral area of L square units, a slant height of l units, and its base has a perimeter of P units, then

Surface Area of a Regular Pyramid • If a regular has a surface area of T square units, a slant height of l units, and its base has a perimeter of P units and an area of B square units, then

Lateral Area and Surface Area of a Right Circular Cone • If a right circular cone has a lateral area of L square units, a surface area of T square units, a slant height of l units, and the radius of the base is r units, then

In-Class Examples

Homework 11 -4 Worksheet