6th Grade Math Textbook, Fundamentals

Lesson 10-2 for exercise sets. &KDSWHU 

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Find the perimeter of the polygon.

1.Rectangle: 101 m; w22 m 2.Regular heptagon: s47.6 cm

Find the side length of the regular polygon with the given perimeter.

3.Nonagon: P48.6 in. 4.Square: P1024 mm 5.Hexagon: P3913.2 ft

6.Discuss and Write If you know the perimeter of a rectangle,

can you find its dimensions? Explain your answer.

When finding the perimeter of a polygon that is not regular and has no

special formula, sometimes you need to use information given in the

diagram or the description to help find unlabeled dimensions.

Find the perimeter of the polygon.

Notice that the segment labeled 5.1 kmis inside

of the figure; it is not a side.

Only two sides are labeled. However, the tick

marks show that two of the unlabeled sides are

congruent to the segment labeled 5.1 km, and

one is congruent to the side labeled 7.5 km.

Add the side lengths to find the perimeter.

P5.1 5.1 7.5 7.5 9.3 34.5 km

7.5 km

9.3 km

5.1 km

Find the perimeter of the polygon.

The figure has 12 sides. Only one side

length is given. However, the markings

show that four of the sides are 18.9 in.

long and eight of the sides are 14.6 in.

long.

You can use multiplication and addition

to find the perimeter.

P4(18.9) 8(14.6) 192.4 in.

18.9 in.

14.6 in.

Remember:

Identical tick marks

show congruency

or equal measures.

If all the side lengths of a polygon are multiplied by the same number,

the perimeter will also be multiplied by that number.

Find the perimeter of a square with sides of length 6x.

Then find the perimeter if the side lengths are tripled.

Original square: New square:

P 4 sP 4 s

4(6x) 4(3 • 6x)

 24 x  72 x

So tripling the side lengths of the square triples the perimeter.

Think

(24x)3  72 x