SAT Math : How to find the perimeter of a rectangle

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : How To Find The Perimeter Of A Rectangle

A rectangle has a width of 2x. If the length is five more than 150% of the width, what is the perimeter of the rectangle?

Possible Answers:

10(x + 1)

6x2 + 5

6x2 + 10x

5x + 10

5x + 5

Correct answer:

10(x + 1)

Explanation:

Given that w = 2x and l = 1.5w + 5, a substitution will show that l = 1.5(2x) + 5 = 3x + 5.  

P = 2w + 2l = 2(2x) + 2(3x + 5) = 4x + 6x + 10 = 10x + 10 = 10(x + 1)

Example Question #1 : How To Find The Perimeter Of A Rectangle

Find the perimeter of a rectangle with width 7 and length 9.

Possible Answers:

Correct answer:

Explanation:

To solve, simply use the formula for the perimeter of a rectangle.

Substitute in the width of seven and the length of nine.

Thus,

Example Question #2 : How To Find The Perimeter Of A Rectangle

Find the perimeter of a rectangle whose side lengths are 1 and 2.

Possible Answers:

Correct answer:

Explanation:

To solve, simply use the formula for the perimeter of a rectangle. Thus,

Example Question #3 : How To Find The Perimeter Of A Rectangle

Find the perimeter of a rectangle with width 6 and length 9.

Possible Answers:

Correct answer:

Explanation:

To solve, simply use the formula for the perimeter.

Another way to solve this problem is to add up all of the sides. Remember that even though only two values are given, a rectangle has 4 sides. Thus,

Example Question #2 : How To Find The Perimeter Of A Rectangle

You have a poster of one of your favorite bands that you are planning on putting up in your dorm room. If the poster is 3 feet tall by 1.5 feet wide, what is the perimeter of the poster?

Possible Answers:

Correct answer:

Explanation:

You have a poster of one of your favorite bands that you are planning on putting up in your dorm room. If the poster is 3 feet tall by 1.5 feet wide, what is the perimeter of the poster?

Perimeter of a rectangle is found via:

Example Question #3 : How To Find The Perimeter Of A Rectangle

Three of the vertices of a rectangle on the coordinate plane are located at the origin, , and . Give the perimeter of the rectangle.

Possible Answers:

Correct answer:

Explanation:

The rectangle in question is below:

Rectangle 3

The lengths of the rectangle is 10, the distance from the origin to ; its width is 7, the distance from the origin to . The perimeter of a rectangle is equal to twice the sum of its length and width, so calculate:

.

Example Question #1 : How To Find The Perimeter Of A Rectangle

A rectangular garden has an area of . Its length is  meters longer than its width. How much fencing is needed to enclose the garden?

Possible Answers:

Correct answer:

Explanation:

We define the variables as  and .

We substitute these values into the equation for the area of a rectangle and get

 or 

Lengths cannot be negative, so the only correct answer is . If , then

Therefore, .

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