SSAT Middle Level Math : How to find perimeter of a triangle

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

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Example Questions

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Example Question #1 : How To Find Perimeter Of A Triangle

The perimeter of an isosceles triangle is 18.  What is a possible list of the lengths of the sides?

Possible Answers:

Correct answer:

Explanation:

Since it is isosceles, 2 of the sides must be equal.  They must also add to 18. 

Example Question #23 : Plane Geometry

An equilateral triangle has perimeter 8 feet 6 inches. How long is one side?

Possible Answers:

3 feet 4 inches

2 feet 2 inches

3 feet 2 inches

2 feet 10 inches

2 feet 6 inches

Correct answer:

2 feet 10 inches

Explanation:

One foot is equal to 12 inches, so the perimeter 8 feet 6 inches is equal to  inches.

An equilateral triangle has three sides of equal measure, so divide its perimeter by 3:

To convert 34 inches to feet and inches:

One side measures 2 feet 10 inches.

Example Question #64 : Geometry

Q_5

Find the perimeter of the triangle above.

Note: Figure not drawn to scale.

Possible Answers:

None of these answers are correct.

Correct answer:

Explanation:

The perimeter of a shape is the length around the shape. In order to find the perimeter of a triangle, add the lengths of the sides: .

Because the lengths are in inches, the answer must be in inches as well.

Example Question #24 : Plane Geometry

If the triangle below is an isosceles triangle, what of the following choices could be its perimeter?

Slide1

Possible Answers:

20

15

21

19

12

Correct answer:

19

Explanation:

An isosceles triangle has 2 equal sides and a third side that is unequal. If one given side is 5 and the other is 7, then the third missing side must equal either 5 or 7. If the missing side has length 5, then the perimeter is 17 (5+5+7). If the missing side is of length 7, then the perimeter is 19 (7+7+5). Of the two, only 19 is an answer choice, so the correct answer is 19.

Example Question #2 : How To Find Perimeter Of A Triangle

The perimeter of equilateral triangle QRS is 4 times the perimeter of equilateral triangle TUV. If the perimeter of QRS is 36, what is the length of one side of TUV?

Possible Answers:

18

9

12

4

3

Correct answer:

3

Explanation:

If the perimeter of QRS is 4 times the perimeter of TUV, and the perimeter of QRS is 36, then the perimeter of TUV is equal to 36 divided by 4, which is 9. If the perimeter of equilateral triangle TUV is 9, then each individual side must have length 3. 

Example Question #26 : Plane Geometry

What is the perimeter, in feet, of an equilateral triangle that has a side of 36 inches?

Possible Answers:

Correct answer:

Explanation:

Given that there are 12 inches in a foot, 36 inches is equal to 3 feet because 36 divided by 12 equals 3. 

In an equilateral triangle, each side is equal. Thus, if one side is 3 feet long, that means that each of the other two sides are also 3 feet long. 

Add the sides together to find the total perimeter.

The perimeter of the triangle is 9 feet. 

Example Question #27 : Plane Geometry

The perimeter of an isosceles triangle is 19. What is the possible list of the lengths of the sides?

Possible Answers:

Correct answer:

Explanation:

Since the triangle is an isoscles, two of the sides must be equal. They must also add to . Looking at the possibilities, only  have two sides that are the same length. Now we need to check the triangle inequality to make sure the lengths create a triangle. The triangle inequality is:

Plugging   into these inequalities we get:

 

Therefore, the inequalities hold true thus,  creates a triangle. Now we need to look at the sum of the lengths:

Therefore,  is the correct answer.

Example Question #1 : Geometry

A triangle has sides  feet,  feet, and  feet. Calculate its perimeter.

Possible Answers:

Correct answer:

Explanation:

The perimeter of any figure is the sum of the lengths of the sides: .

Example Question #3 : How To Find Perimeter Of A Triangle

A right triangle with hypotenuse 65 has one leg of length 60. What is its perimeter?

Possible Answers:

Correct answer:

Explanation:

By the Pythagorean Theorem, if  and  are the legs of a right triangle and  is its hypotenuse, then 

.

Set  and solve for :

The perimeter of the triangle - the sum of the sidelengths - is 

.

Example Question #4 : How To Find Perimeter Of A Triangle

What is the perimeter of an equilateral triangle with a side length ?

Possible Answers:

Correct answer:

Explanation:

The perimeter is equal to the sum of the length of the sides. An equilateral triangle has three sides with equal lengths.

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