Exercise 21 Page 16

Practice makes perfect

Let's take a look at the given rectangle.

A rectangle has two pairs of equal sides, so we can find its perimeter using the following formula. P=2l+2w In this formula, l is the length and w is the width. From the picture, we know that l is equal to 8 centimeters, and w is equal to 3 centimeters.

P=2l+2w

SubstituteII

l= 8, w= 3

P=2( 8)+2( 3)

Multiply

P=16+6

AddTerms

Add terms

P=22

The rectangle's perimeter is 22 centimeters.

Let's take a look at the given trapezoid.

The perimeter measures the distance around the outside of a figure. To determine the perimeter of a figure, all of its side lengths must be added. Let's add the side lengths of the given trapezoid! P= 5cm+3cm+9cm+3cm = 20cm The perimeter of the trapezoid is 20 centimeters.

Let's take a look at the given triangle.

The perimeter measures the distance around the outside of a figure. To determine the perimeter of a figure, all of its side lengths must be added. Let's add the side lengths of the given triangle! P= 13in.+12in.+5in. = 30in. The perimeter of the triangle is 30 inches.

Let's take a look at the given triangle.

The perimeter measures the distance around the outside of a figure. To determine the perimeter of a figure, all of its side lengths must be added. Let's add the side lengths of the given triangle! P= 6mm+3mm+4mm = 13mm The perimeter of the triangle is 13 millimeters.

Let's take a look at the given figure.

The perimeter measures the distance around the outside of a figure. To determine the perimeter of a figure, all of its side lengths must be added. In this case, all the sides have the same length so we can find its perimeter using the following formula. P=a+a+a+a ⇔ P=4a In this formula, a is the length of each side. From the picture, we know that a is equal to 4 feet. Substituting this value into the formula, we can calculate P.

P=4a

Substitute

a= 4

P=4( 4)

Multiply

P=16

The perimeter of the figure is 16 feet.

Let's take a look at the given triangle.

The perimeter measures the distance around the outside of a figure. To determine the perimeter of a figure, all of its side lengths must be added. Let's add the side lengths of the given triangle! P= 10m+10m+5m = 25m The perimeter of the triangle is 25 meters.

Subchapter links

1.1.2 Perimeter and Area Relationships p.10-11

1.1.3 Describing and Extending Patterns p.15-16

1.1.4 Representing Data p.21-22

1.1.5 Making Sense of a Logic Problem p.25-26

Exercise 21 Page 16

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