Chapter 11.2 Surface Areas of Prisms and Cylinders

Vocabulary• Prism = a polyhedron with exactly two

congruent, parallel faces, called bases. Other faces are lateral faces. You name a prism by the shape of its bases

Examples:

• Right prisms Oblique Prisms

Vocabulary

• Altitude = perpendicular segment that joins the planes of the bases

• Height = the length of altitude

Vocabulary

• Lateral area = the sum of the areas of the lateral faces

• Surface area = sum of the lateral area and the area of the two bases

Theorem 11.1 lateral and Surface Areas of a Prism

• The lateral area of a right prism is the product of the perimeter of the base and the height

• P = perimeter of base• H= height

phAL ..

Theorem 11.1 lateral and Surface Areas of a Prism

• The surface area of a right prism is the sum of the lateral area and the areas of the two bases

• B= area of base

BALAS 2....

Example #1

• Find the lateral area and total surface area of the prism

Theorem 11.2 lateral and Surface Areas of a Cylinder

• The lateral area of a right cylinder is the product of the circumference of the base and the height of the cylinder

rhAL 2..

Theorem 11.2 lateral and Surface Areas of a Cylinder

• The surface area of a right cylinder is the sum of the lateral area and the areas of the two bases

222..

2....

rrhAS

BALAS

Example #1

• Find the lateral surface area of a cylinder with a base radius of 3 inches and a height of 9 inches.

• L. S. A. = 2π(3)(9) = 54π inches2

                  

Example #2

• Find the total surface area of a cylinder with a base radius of 5 inches and a height of 7 inches

• T. S. A. = 2π(5)(7) + 2π(5)2 = 70π + 50π

 = 120π inches2  

Important

• You need to know the concept of lateral face and surface area.

• For the right prisms, you know that the lateral surface is a rectangle, you know the area of the rectangle and you can then multiply by however many there are.

Classwork/Homework

• Pgs 611-613 #1-16, 34