SSAT Upper Level Math : How to find the perimeter of an acute / obtuse triangle

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

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Example Questions

Example Question #11 : How To Find The Perimeter Of An Acute / Obtuse Triangle

Find the perimeter of the triangle below:

4

Possible Answers:

\displaystyle 13

\displaystyle 12

\displaystyle 11

\displaystyle 14

Correct answer:

\displaystyle 13

Explanation:

First, find the length of the missing side.

Since the angle measurements in the base of the triangle are the same, this is an isosceles triangle. The side lengths directly across from the equal angles must be the same. Thus, the missing side length is \displaystyle 5.

Now, to find the perimeter, add up all the side lengths.

\displaystyle \text{Perimeter}=5+5+3=13

Example Question #12 : How To Find The Perimeter Of An Acute / Obtuse Triangle

Find the perimeter of the triangle below:

3

Possible Answers:

\displaystyle 40

\displaystyle 60

\displaystyle 70

\displaystyle 50

Correct answer:

\displaystyle 50

Explanation:

First, find the length of the missing side.

Since the angle measurements in the base of the triangle are the same, this is an isosceles triangle. The side lengths directly across from the equal angles must be the same. Thus, the missing side length is \displaystyle 16.

Now, to find the perimeter, add up all the side lengths.

\displaystyle \text{Perimeter}=16+16+18=50

Example Question #13 : How To Find The Perimeter Of An Acute / Obtuse Triangle

Find the perimeter of the triangle below:

2

Possible Answers:

\displaystyle 60

\displaystyle 61

\displaystyle 57

\displaystyle 47

Correct answer:

\displaystyle 57

Explanation:

First, find the length of the missing side.

Since there are two angles that are the same, this is an isosceles triangle. The side lengths directly across from the equal angles must be the same. Thus, the missing side length is \displaystyle 18.

Now, to find the perimeter, add up all the side lengths.

\displaystyle \text{Perimeter}=18+18+21=57

Example Question #14 : How To Find The Perimeter Of An Acute / Obtuse Triangle

Find the perimeter of the triangle below:

1

Possible Answers:

\displaystyle 58

\displaystyle 54

\displaystyle 44

\displaystyle 48

Correct answer:

\displaystyle 48

Explanation:

First, find the length of the missing side.

Since there are two angles that are the same, this is an isosceles triangle. The side lengths directly across from the equal angles must be the same. Thus, the missing side length is \displaystyle 14.

Now, to find the perimeter, add up all the side lengths.

\displaystyle \text{Perimeter}=14+14+20=48

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