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

## Example Questions

### Example Question #11 : How To Find The Perimeter Of A Triangle

If the sides of a triangle are equal to 5, 6, and 2x, what is the value of x if the perimeter is 23?

Explanation:

The perimeter of a triangle is equal to the sum of its sides. Given that the sides are equal to 5, 6, and 2x, and the perimeter is 23, the appropriate equation to use would be:

(Subtract 11 from each side of the equation.)

(Divide each side of the equation by 2.)

### Example Question #11 : How To Find The Perimeter Of A Triangle

What is the perimeter of an equilateral triangle for which each side is equal to 4.5?

Explanation:

The perimeter is equal to the sum of the sides of the shape. For an equilateral, all sides are equal. This allows us to simply multiply the given length by 3.

### Example Question #332 : Plane Geometry

If two sides of a triangle measure  inches and  inches, which of the following is NOT a possible length (in inches) of the third side?

Explanation:

In a triangle, the length of a third side cannot equal or exceed the sum of the other two sides. The sum of the other two sides is equal to . Therefore, the third side cannot be  inches or greater. Thus, since  is greater than , that cannot be the length of the third side. Thus,  is the correct answer.

### Example Question #12 : How To Find The Perimeter Of A Triangle

The sides of a triangle are equal to  inches,  foot, and  inches. What is the perimeter of the triangle in inches?

Explanation:

The perimeter of a triangle is equal to the sum of its sides.

If the sides of a triangle are equal to  inches,  foot, and  inches, the first step is convert all the sides to inches. This results in:

### Example Question #13 : How To Find The Perimeter Of A Triangle

If the perimeter of a triangle is equal to  inches, and its sides are equal to , , and , what is the length of the longest side (in inches)?

Explanation:

If the perimeter of a triangle is equal to  inches, and its sides are equal to , and , the following equation can be used to determine the value of :

Divide each side of the equation by

Given that the longest side of the triangle is equal to , the longest side is . Therefore,  is the correct answer.

### Example Question #14 : How To Find The Perimeter Of A Triangle

In an equilateral triangle, the value of one side is equal to . If the perimeter is equal to 18, what is the value of x?

Explanation:

The perimeter of an equilateral triangle will be 3 multiplied by one side.

Therefore, the following equation would apply:

Applying the distributive property, the following equation results:

Next, we subtract 12 from each side.

Divide both sides by 3.

### Example Question #15 : How To Find The Perimeter Of A Triangle

If you have a right triangle with a height of 6 inches, a base of 8 inches, and a hypotenuse of 10 inches, what is its perimeter?

Explanation:

If you have a right triangle with a height of 6 inches, a base of 8 inches, and a hypotenuse of 10 inches, what is its perimeter?

Recall that to find perimeter, we simply need to add up the lengths of all the sides.

So our answer must be 24 inches

### Example Question #61 : Triangles

An isosceles triangle measures  inches along its two equal sides, and  inches along its third side.  What is the perimeter of the triangle?

Explanation:

To find the perimeter of any shape, simply add the length of each side together.  The best answer is:

### Example Question #16 : How To Find The Perimeter Of A Triangle

An equilateral triangle measures  inches along its three equal sides.  What is the permiter of the triangle?

Explanation:

To find the perimeter of any object, simply add the length of each side together.  The best answer is:

### Example Question #17 : How To Find The Perimeter Of A Triangle

An equilateral triangle measures  inches along its three equal sides.  What is the perimeter of the triangle?