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

## Example Questions

### Example Question #31 : How To Find The Perimeter Of A Triangle

Find the perimeter of an equilateral triangle with a base of 12 cm.

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 12cm.  Because it is an equilateral triangle, we know that all the sides are equal.  In other words, all sides are 12cm.  Knowing this, we can substitute into the formula.  We get

### Example Question #351 : Plane Geometry

Use the following to answer the question.

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

we can see it has sides with lengths of 9 inches, 3 inches, and 10 inches.  Knowing all of this, we can substitute into the formula.  We get

### Example Question #31 : How To Find The Perimeter Of A Triangle

What is the perimeter of an isosceles triangle with a base of  and a side length of ?

Cannot determine

Explanation:

An isosceles triangle has a set of equal sides so the base is  and the other two will be  apiece.

The perimeter is all three sides added up so the perimeter will be

### Example Question #31 : How To Find The Perimeter Of A Triangle

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

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 9 feet.  Because it is an equilateral triangle, we know that all sides are equal.  This means that all sides are 9 feet.  Knowing this, we can substitute into the formula.  We get

### Example Question #31 : How To Find The Perimeter Of A Triangle

Find the perimeter of an equilateral triangle with a base of 4 feet.

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 4 feet.  Because it is an equilateral triangle, we know that all sides are equal.  Therefore, all sides are 4 feet.  Knowing this, we can substitute into the formula.  We get

### Example Question #355 : Plane Geometry

Use the following equilateral triangle to answer the question:

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, let's look at the equilateral triangle.

We can see that one side has a length of 4ft.  Because it is an equilateral triangle, all sides are equal.  Therefore, all sides are 4ft.

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

### Example Question #356 : Plane Geometry

Use the following triangle to solve the problem:

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, let's look at the triangle.

We can see the lengths of the sides are 9in, 3in, and 10in.

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

### Example Question #31 : How To Find The Perimeter Of A Triangle

Use the following triangle to answer the question:

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

we can see the lengths of the sides are 11cm, 6cm, and 12cm.

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

### Example Question #358 : Plane Geometry

Use the following triangle to answer the question:

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

we can see it has sides of length 8ft, 4ft, and 7ft.

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

### Example Question #31 : How To Find The Perimeter Of A Triangle

Find the perimeter of an equilateral triangle with a base of length 10cm.

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 a triangle.

Now, we know the base of the triangle is 10cm.  Because it is an equilateral triangle, all sides are equal.  Therefore, all sides are 10cm.

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