7th Grade Math

Reinforcement

of GLE 0606.3.4. Use

expressions, equations

and formulas to solve

problems.

16 Start Smart

The Pentagon

The Pentagon in Washington, D.C., is the

headquarters of the nation’s Defense

Department. Although it has 17.5 miles

of hallways, it takes at most seven

minutes to walk between any two points

because of its unusual design.

PENTAGON The sides of a regular polygon are equal in length. The

Pentagon in Washington, D.C., is an example of a regular pentagon. The

length of each exterior wall measures 921 feet. What is the perimeter of

the exterior of the Pentagon?

The distance around a geometric figure is called the perimeter.

Find the Perimeter

PENTAGON Refer to the information above. Suppose you walked

the perimeter of the Pentagon. What is the total distance you

walked?

P = 5 s Perimeter of a regular pentagon

P = 5( 921 ) Replace s with 921.

P = 4,605 Multiply.

You walked 4,605 feet.

a. ART A poster in the shape of a triangle has side lengths of

25 centimeters, 30 centimeters, and 35 centimeters. What is the

perimeter of the poster?

b. PHYSICAL EDUCATION In physical education class, Mrs. Uhrlacher

had the students run around the perimeter of the gym twice.

The gym is 111 feet long and 107 feet wide. How far did the

students run?

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