How to find the perimeter of a triangle

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SSAT Elementary Level Quantitative › How to find the perimeter of a triangle

Questions 1 - 10
1

Find the perimeter of an equilateral triangle with side length 1.

Explanation

To solve, simply use the formula for the perimeter of an equilateral triangle. Thus,

Remember, the special property of an equilateral triangle is that all of its sides are the same length so, you can either add the side length 3 times or multiply it by 3.

2

You can find the perimeter of a triangle if you know __________.

three side lengths

the height and base

the area

its angles

Explanation

3

A triangle has the side lengths , , and . What is the perimeter of the triangle?

Explanation

The perimeter of a triangle is the sum of the three sides.

Add the lengths together to find the perimeter.

4

What is the PERIMETER of the triangle in the figure? Screen_shot_2014-01-31_at_4.13.52_pm

30 cm

Explanation

Because the question asks you to find the PERIMETER of the triangle, you are looking to figure out the distance around the outside of the triangle. You find the perimeter of triangles simply by adding the length of the three sides together. So the correct answer here is , or .

5

What is the PERIMETER of the triangle in the figure?

Screen_shot_2014-01-31_at_4.17.07_pm

Explanation

Because the question asks you to find the PERIMETER of the triangle, you are looking to figure out the distance around the outside of the triangle. You find the perimeter of triangles simply by adding the length of the three sides together. So the correct answer here is , or .

6

What shape has only angles?

Triangle

Square

Cube

Pentagon

Hexagon

Explanation

A triangle is the only shape with angles.

Screen shot 2015 09 09 at 12.06.52 pm

7

What is the PERIMETER of the triangle in the figure?

Screen_shot_2014-01-31_at_4.18.55_pm

Explanation

Because the question asks you to find the PERIMETER of the triangle, you are looking to figure out the distance around the outside of the triangle. You find the perimeter of triangles simply by adding the length of the three sides together. So the correct answer here is , or .

8

The perimeter of a scalene triangle is 21 mm. Which choice shows the correct side lengths?

Explanation

When finding the perimeter of any triangle, you will need to add all three sides. In this case, it is important to note that this is the perimeter of a scalene triangle. A scalene triangle has no congruent/equal sides. The only choice that adds up to 21 mm with no equal sides is:

9

Use the following triangle to solve the problem:

Triangle2

Find the perimeter.

Explanation

To find the perimeter of a triangle, we will use the following formula:

where a, b, and c are the lengths of the sides of the triangle.

Now, given the triangle

Triangle2

we can see it has sides of length 11cm, 6cm, and 12cm. So, we can substitute. We get

10

Find the perimeter of an equilateral triangle with a base of 16in.

Explanation

To find the perimeter of a triangle, we will use the following formula:

where a, b, and c are the lengths of the sides of the triangle.

Now, we know the base of the triangle has a length of 16in. Because it is an equilateral triangle, all lengths are the same. Therefore, all lengths are 16in.

Knowing this, we can substitute into the formula. We get

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