ISEE Middle Level Math : How to find the perimeter of a triangle

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

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Example Questions

Example Question #31 : Plane Geometry

Find the perimeter of an equilateral triangle with a side of length 7in.

Possible Answers:

Correct answer:

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 equilateral triangle has one side of length 7in.  Because it is an equilateral triangle, all sides are equal.  Therefore, all sides are 7in.  So, we can substitute.  We get

Example Question #32 : Plane Geometry

Find the perimeter of an equilateral triangle with a base of 13in.

Possible Answers:

Correct answer:

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 is 13in.  Because it is an equilateral triangle, all sides are equal.  Therefore, all sides are 13in.  So, we get

Example Question #33 : Geometry

Find the perimeter of an equilateral triangle with a base of length 9in.

Possible Answers:

Correct answer:

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 9in. Because it is an equilateral triangle, all lengths are the same. Therefore, all lengths are 9in.

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

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