SSAT Elementary Level Math : Plane Geometry

Study concepts, example questions & explanations for SSAT Elementary Level Math

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Example Questions

Example Question #14 : How To Find The Perimeter Of A Rectangle

How many sides does a rectangle have?

Possible Answers:

5

3

1

4

2

Correct answer:

4

Explanation:

A rectangle is a shape with 4 sides.  The opposite sides have equal lengths.

Example Question #15 : How To Find The Perimeter Of A Rectangle

Screen_shot_2014-10-10_at_9.19.31_pm

What is the perimeter of the above rectangle?

Possible Answers:

\(\displaystyle 83\)

\(\displaystyle 24\)

\(\displaystyle 11\)

\(\displaystyle 16\)

\(\displaystyle 22\)

Correct answer:

\(\displaystyle 22\)

Explanation:

To find the perimeter of the rectangle, add all four sides together. Even though we are not given the length of all four sides, we know that opposite sides are always equal. 

\(\displaystyle 8 + 3 + 8 + 3 = 22\)

Example Question #16 : How To Find The Perimeter Of A Rectangle

Screen_shot_2014-11-13_at_2.50.26_pm

What is the perimeter of the blue rectangle?

Possible Answers:

\(\displaystyle 28\)

\(\displaystyle 24\)

\(\displaystyle 32\)

\(\displaystyle 100\)

\(\displaystyle 29\)

Correct answer:

\(\displaystyle 28\)

Explanation:

To find the perimeter of the rectangle, add all four sides together. Even though we are not given the length of all four sides, we know that opposite sides are always equal. 

\(\displaystyle 12 + 2 + 12 + 2 = 28\)

Example Question #451 : Plane Geometry

House

How many feet of fence do you need to surround the rectangular area in front of the house?

Possible Answers:

\(\displaystyle 92\)

\(\displaystyle 68\)

\(\displaystyle 102\)

\(\displaystyle 72\)

\(\displaystyle 86\)

Correct answer:

\(\displaystyle 92\)

Explanation:

In order to figure out how many feet of fence you need, add up all of the segments that are going to be fenced.  Thus, \(\displaystyle 12+12+18+18+36= 92\).  Remember, you will not need to put fence where the house is.

Example Question #18 : How To Find The Perimeter Of A Rectangle

A rectangle has sides of lengths \(\displaystyle 14\) and \(\displaystyle 27\). What is its perimeter?

Possible Answers:

\(\displaystyle 84\)

\(\displaystyle 90\)

\(\displaystyle 86\)

\(\displaystyle 82\)

\(\displaystyle 80\)

Correct answer:

\(\displaystyle 82\)

Explanation:

Since a rectangle has two sets of equal sides, the perimeter is the sum of twice each of the two sides given. \(\displaystyle 2\cdot14=28\) and \(\displaystyle 2\cdot27=54\)\(\displaystyle 28+54=82\), which is the answer.

Example Question #19 : How To Find The Perimeter Of A Rectangle

If a rectangle has a perimeter of \(\displaystyle 40\) units, and one of its sides is of length \(\displaystyle 12\), what are the lengths of its other three sides?

Possible Answers:

\(\displaystyle 10\)\(\displaystyle 10\), and \(\displaystyle 8\)

\(\displaystyle 12\)\(\displaystyle 7\), and \(\displaystyle 7\)

\(\displaystyle 14\)\(\displaystyle 8\), and \(\displaystyle 6\)

\(\displaystyle 12\)\(\displaystyle 10\), and \(\displaystyle 6\)

\(\displaystyle 12\)\(\displaystyle 8\), and \(\displaystyle 8\)

Correct answer:

\(\displaystyle 12\)\(\displaystyle 8\), and \(\displaystyle 8\)

Explanation:

Since rectangles have two sets of equal sides, and one side is of length \(\displaystyle 12\), there must be another side of length \(\displaystyle 12\). Since we know the total perimeter of the rectangle, we can get the length of the two remaining sides by subtracting the two known side lengths from the total perimeter. \(\displaystyle 40-12-12=16\), and since the rectangle must have another set of equal sides, we must split \(\displaystyle 16\) into two equal parts. Therefore, the last two sides must be \(\displaystyle 8\) and \(\displaystyle 8\). This means the rectangle's other three sides must be \(\displaystyle 12\), \(\displaystyle 8\), and \(\displaystyle 8\).

Example Question #20 : How To Find The Perimeter Of A Rectangle

Madison would like to buy a rug to cover the whole floor in her new room. Her room is in the shape of a rectangle and has a perimeter of \(\displaystyle 76\) feet. She measured and one side of her room is \(\displaystyle 15\) feet long. Which of the following rug dimensions would best fit Madison's room?

Possible Answers:

\(\displaystyle 15\: \textup{ft by } 23\: \textup{ft}\)

\(\displaystyle 15 \:\textup{ft by } 21 \:\textup{ft}\)

\(\displaystyle 15 \:\textup{ft by } 46 \:\textup{ft}\)

\(\displaystyle 15 \:\textup{ft by } 33 \:\textup{ft}\)

\(\displaystyle 38 \:\textup{ft by } 38 \:\textup{ft}\)

Correct answer:

\(\displaystyle 15\: \textup{ft by } 23\: \textup{ft}\)

Explanation:

The perimeter is the measurements of all four sides of a square or rectangle. We can use the following formula to solve the problem:

\(\displaystyle \textup{Perimeter} = 2 (\textup{length}) + 2 (\textup{width})\)

We already know that one side is 15 ft and that the total perimeter is 76 ft, so we can plug those numbers into the formula.

\(\displaystyle 76 = 2 (15) + 2 (\textup{w})\)

\(\displaystyle 76 = 30 + 2 (\textup{w})\)

We can subtract 30 from both sides of the equation.

\(\displaystyle 76-30 = 30-30 + 2 (\textup{w})\)

Now we are left with:

\(\displaystyle 46 = 2 (\textup{w})\)

We can divide both sides by 2 to find the width of the room.

\(\displaystyle \frac{46}{2} = \frac{2}{2} \textup{(w)}\)

\(\displaystyle \textup{w} = 23\)

Therefore, the lengths of the other two sides of the room are 23 ft.

To check to see if our answer is correct we can add the four sides of the room:

\(\displaystyle 15 + 15 + 23 + 23 = ?\)

This equals 76! (The perimeter of the room in the problem.)

Madison should buy a rug that is 15 ft. by 23 ft.

Example Question #21 : How To Find The Perimeter Of A Rectangle

Find the perimeter of a rectangle whose width is 5 and length is 7.

Possible Answers:

\(\displaystyle 40\)

\(\displaystyle 12\)

\(\displaystyle 35\)

\(\displaystyle 24\)

Correct answer:

\(\displaystyle 24\)

Explanation:

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

\(\displaystyle P=2(w+l)=2(5+7)=2*12=24\)

Example Question #22 : How To Find The Perimeter Of A Rectangle

Find the perimeter of a rectangle whose side lengths are 9 and 6

Possible Answers:

\(\displaystyle 54\)

\(\displaystyle 30\)

\(\displaystyle 14\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 30\)

Explanation:

To find perimeter of a rectangle, simply use the formula below:

\(\displaystyle P=2(w+l)=2(9+6)=2*15=30\)

Example Question #1 : Apply Area And Perimeter Formulas For Rectangles: Ccss.Math.Content.4.Md.A.3

What is the length of a rectangular room with a perimeter of \(\displaystyle 42ft\) and a width of \(\displaystyle 7ft?\)

Possible Answers:

\(\displaystyle 28ft\)

\(\displaystyle 18ft\)

\(\displaystyle 22ft\)

\(\displaystyle 12ft\)

\(\displaystyle 14ft\)

Correct answer:

\(\displaystyle 14ft\)

Explanation:

\(\displaystyle P=2l+ 2w\)

We have the perimeter and the width, so we can plug those values into our equation and solve for our unknown. 

\(\displaystyle 42=2l+2(7)\)

\(\displaystyle 42=2l+14\)

Subtract \(\displaystyle 14\) from both sides

\(\displaystyle 42-14=2l+14-14\)

\(\displaystyle 28=2l\)

Divide \(\displaystyle 2\) by both sides

\(\displaystyle \frac{28}{2}=\frac{2l}{2}\)

\(\displaystyle 14=l\)

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