Pre-Algebra - Perimeter of a Triangle

Find the perimeter of the triangle above.

Note: Figure not drawn to scale.

None of these answers are correct.

Explanation

The perimeter of a shape is the length around the shape. In order to find the perimeter of a triangle, add the lengths of the sides: .

Because the lengths are in inches, the answer must be in inches as well.

What is the perimeter of an equilateral triangle with a length of 5?

$\frac{15}{2}$

$\frac{3}{2}$

$\textup{There is not enough information.}$

Explanation

There are three equal sides in an equilateral triangle.

Substitute the side length.

$P=3\times 5 =15$

A right triangle has two short sides with lengths 5 and 12. What is the perimeter of the triangle?

Explanation

To begin, first find the length of the third side of the triangle. We are given that the two short sides of the triangle have lengths of 5 and 12. Use the Pythagorean Theorem to find the length of the third side:

$\small a^2+b^2=c^2$ ,

where $\small a$ and $\small b$ represent the two shorter sides of the triangle, and $\small c$ is the hypotenuse:

$\small a^2+b^2=c^2$

$\small \small 5^2+12^2=c^2$

$\small 25+144 = c^2$

$\small 169 = c^2$

$\small \sqrt{169}=\sqrt{c^2}$

$\small c=13$

Now that we have the lengths of all three sides, add them together to find the perimeter:

$\small 5+12+13 = 30$

The perimeter of the triangle is 30.

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

inches

Explanation

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

inches

What is the area of a triangle with a base of units and a height of units?

Explanation

The equation for the area of a tirangle is $(Area) =\frac{1}{2}*(Base)*(Height)$

The base in this equation is and the height is which can be plugged into the formula as:

$(Area) = \frac{1}{2}(14)*(10)$

Finally, we multiply to get:

For an isosceles triangle, if two of the sides are 3 and 6, which of the following is a possible perimeter?

Explanation

In an isosceles triangle, two of the three sides are equal to each other. The possible side lengths of the isosceles are or .

The perimeter is the sum of the three sides.

The only possible perimeters given the two side lengths are either or .

The correct answer is:

An equilateral triangle measures inches along its side. What is the area of the triangle?

square inches

Explanation

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

square inches

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

inches

Explanation

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

inches

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

inches

Explanation

To find the perimeter of any object, simply add the length of each side together. This triangle has sides of 4, 4, and 7, so the answer is:

inches

Find the perimeter of an equilateral triangle with a side of length 14 inches.

$42\textup{ inches}$

$\textup{196 inches}$

$196 \text{ inches}^2$

$42 \text{ inches}^2$

$\textup{72 inches}$

Explanation

The formula for the perimeter of a triangle is

where a, b, and c are the lengths of each side.

We know that an equillateral triangle has 3 equal sides. Therefore,

Therefore, the perimeter of an equillateral triangle with a side of length 14 inches is 42 inches.

Perimeter of a Triangle

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