7th Grade Math

584 Volume and Surface Area

To find the surface area of a triangular prism, it is more efficient to

find the area of each face and calculate the sum of all of the faces

rather than using a formula.

Surface Area of

Triangular Prisms

PACKAGING Marty is mailing his aunt

3 .6 in.

14 in 14 in.

3. 66 in.

44 in.

3 3in in.

a package and is using a container

that is a triangular prism. The height

is 14 inches. The triangular base has

a height of 3 inches and a base of

4 inches. How much cardboard is

used to create the shipping container?

To find the surface area of the container, find the area of each face

and add.

4 in.

3 in.

3.6 in.

14 in.

4 in.

3 in.

3.6 in.

14 in.

4 in.

14 in.

The area of each triangle is _ 21 · 4 · 3 or 6.

The area of two of the rectangles is 14 · 3.6 or 50.4. The area of the

third rectangle is 14 · 4 or 56.

The sum of the areas of the faces is 6 + 6 + 50.4 + 50.4 + 56 or

168.8 cubic inches.

Find the surface area of each triangular prism.

d.

9 mm

12 mm

21 mm 15 mm

e. 5 in.

7 in.

10 in.

5 in.

5 in. 5 in.

f.

2 cm

2.5 cm

3 cm

4 cm

g.

4 m

5 m

6 m

3 m

Area Area When finding the

area of a rectangle, the

side lengths can be

referred to as length 

and width w or base b and

height h.

A = w or A = bh

Everyday Use

Base the bottom of an

object

Math Use

Base one of two parallel

congruent faces of a prism

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