Page 122 - Math Course 1 (Book 2)

Lateral and Surface Area of Prisms and Cylinders

MO. 10 - L3b Estimate (2 • 3 • 5 • 8) + (2 • 5 • 5 ) or 390 m 2
2
Lateral and Surface Area Find the lateral area

of Cylinders L = 2πrh

= 2π(5)(8)
Key Concept = 80π exact answer.

≈ 251.3 m 2 approximate answer.
Lateral Area and Surface Area of Cylinders
Find the surface area.
The lateral area L of a cylinder with S = L + 2πr 2
Words radius r and height is the circumference
of the base (2πr) times the height h. = 80π + 2π(5) 2
= 130π exact answer.
Symbols L = 2πrh
= 408.4 m 2 approximate answer.
The surface area S of a cylinder is the
Words lateral area L plus the area of the two How does your estimate compare to your answer?
2
bases (2πr ).
The lateral area is about
Symbols S = L + 2B or S = 2πrh + 2πr 2 251.3 square inches and the
Answer
surface area is about 408.4
Model square inches.
circumference of base
= 2πr
r Real World Example

CEREALS
A company packages its cereal in a rectangular
h
prism that is 2.5 inches by 7 inches by 12 inches.
It is considering packaging it in a cylinder- shaped
area of bases container having a 6-inch diameter and a height
= πr 2 of 7.5 inches. Which uses the least amount of
packaging?

Let’s Begin

Surface Area of Prisms Surface Area of Rectangular Prism Style

Examples Lateral Area Area of Bases

S = L + 2B
5 in.
= Ph + 2ℓw
Find the lateral area = (2 • 7 + 2 • 2.5)(12) + 2(7)(2.5)
and surface area of
the cylinder. Round to 8 in. = 263 in 2
the nearest tenth.

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