Geometry - Pre-Algebra

Card 0 of 1400

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

Tap to see back →

To find the perimeter of any object, simply add the length of each side together.

The best answer is:

$\P=s+s+s\=3s\=3(3)\=9$

nine inches

What is the circumference of a circle with a radius equal to ?

Tap to see back →

The circumference can be solved using the following equation:

$C=2r\pi=2(7)\pi=14\pi$

The perimeter of a given rectangle is equal to the circumference of a given circle. The circle has radius inches; the width of the rectangle is $8 \pi$ inches. What is the length of the rectangle?

Tap to see back →

The circumference of a circle with radius inches is

$C = 2 \pi r = 2 \pi \cdot 30 = 60 \pi$ inches.

The perimeter of the rectangle is therefore $60 \pi$ inches. To find its length, substitute $W = 8\pi$ and $P = 60\pi$ into the equation and solve for :

$2 L + 2 \cdot 8 \pi = 60 \pi$

$2 L + 16 \pi = 60 \pi$

$2 L + 16 \pi - 16 \pi = 60 \pi - 16 \pi$

$2 L =44 \pi$

$2 L \div 2=44 \pi \div 2$

$L = 22\pi$ inches

What is the circumference of a circle with an area equal to $81\pi$ ?

Tap to see back →

Using the area, solve for the radius:

Divide by $\pi$ :

Take the square root:

$$\sqrt{81}$=9=r$

Plug this radius into the formula for the circumference:

$C=2r\pi=2(9)\pi=18\pi$

Becky's house is surrounded by a circular lake that Becky runs around each day. If Becky wants to figure out the distance she runs around the lake, what formula should Becky use?

Tap to see back →

Becky should use the circumfrence formula to find the distance she runs of a lake.

Correct Answer: $C=2\Pi r$

What is the circumference of a circle with a radius of ?

Tap to see back →

The circumference can be solved using the following equation:

$C=2r\pi$

Where represents the radius. Therefore, when we substitute our radius in we get:

$=2(8)\pi =16\pi$

Determine the circumference of the circle if the radius is 20.

Tap to see back →

Write the formula for circumference.

$C=2\pi r$

Substitute the radius and solve.

$C=2\pi(20) = 40\pi$

Given the area of the circle is $9\pi$ , what is the circumference of the circle?

Tap to see back →

Write the formula for the area of a circle.

$A=\pi $r^2$$

Substitute the area.

$9\pi=\pi $r^2$$

Write the circumference of the circle.

$C=2\pi r$

Substitute the radius.

$C=2\pi (3) = 6\pi$

Find the circumference of the circle with a diameter of $2\pi$ .

Tap to see back →

Write the formula for the circumference of a circle.

$C=\pi D = 2\pi r$

Substitute the diameter.

$C=\pi (2\pi) = 2\pi ^2$

Michelle wants to put a fence up around all four sides of her rectangular garden, which measures 10 ft. long and 15 ft. wide. How long will her fence be?

Tap to see back →

Since the perimeter marks out the distance around a shape, you can imagine yourself walking around a shape to find the perimeter. For a rectangle, you would walk the same length twice (once on each side) and the same width twice (once on each side). That's why you multiply both the length and the width by 2.

To find the perimeter, use the following formula:

Step 1: insert length and width into the formula

Step 2: solve

Find the circumference of a circle with an area of .

Tap to see back →

Write the area formula in order to find the radius.

$A=\pi $r^2$$

Substitute the area.

$\pi ^2=\pi $r^2$$

$r=$\sqrt{\pi}$$

Write the circumference formula.

$C=2\pi r$

Substitute the radius.

$C=2\pi $\sqrt{\pi}$$

Determine the circumference of the circle if the radius is $2\pi$ .

Tap to see back →

Write the formula for the circumference of a circle.

$C=2\pi r$

Substitute the radius into the formula.

$C=2\pi (2\pi) = 4\pi ^2$

Find the circumference of a circle with a radius of $\sqrt2$ .

Tap to see back →

Write the formula to find the circumference of a circle.

$C=2\pi r$

Substitute the radius.

$C=2\pi $\sqrt{2}$$

Find the circumference of a circle with an area of 5.

Tap to see back →

Write the formula for the area of a circle.

$A=\pi $r^2$$

Substitute the area to find the radius.

In order to solve the equation, we have to isolate the variable. We do this by performing the same operation to either side of the equation.

$5=\pi $r^2$$

$\frac{5}{\pi $}$=r^2$

$r=$\sqrt{\frac{5}{\pi}$}$

Write the formula to find the circumference of the circle.

$C=2\pi r$

Substitute the radius.

$C=2\pi $\sqrt{\frac{5}{\pi}$}$

If $\pi = 3.14$ find the circumference of a circle with a diameter of 10 inches.

Tap to see back →

To solve, we will use the formula for circumference of a circle. The formula is

$C = 2 \pi r$

where $r = $\text{ radius}$$ . We know that the diameter of the circle is 10 inches. To find the radius, we simply divide by 2.

Therefore,

We know $\pi = 3.14$ , so we will substitute. We get

$C = 2 \cdot 3.14 \cdot 5 $\text{ inches}$$

$C = 31.4 $\text{ inches}$$

Therefore, the circumference of the circle is 31.4 inches.

Find the circumference of a circle with a radius of 6cm.

Tap to see back →

The formula to find the circumference of a circle is

$C = \pi d$

where d is the diameter. We know the radius is 6cm. We also know to find the diameter, we take two times the radius. Therefore, the diameter is 12cm. So, substituting into the formula, we get

$C = \pi \cdot 12$

or

$C = 12\pi$

Therefore, the circumference of the cirlce is $12\pi$ .

A circle has a radius of . What is its circumference?

Tap to see back →

The formula for the circumference of a circle is

$C=2\pi r$ .

So, we simply plug in the radius of in order to solve for the circle's circumference:

$C=2\pi (19)$

$C=38\pi$

Therefore, the circumference of ths circle is $38\pi$ .

What is the distance around a silo, if the distance from the center of the silo to the outside is ?

Tap to see back →

What is the distance around a silo, if the distance from the center of the silo to the outside is ?

Picture a silo, its base is a circle.

This problem want the circumference of that circle. It gives us the distance from the center to the outside of the circle, aka the radius.

Find circumference via the following formula:

$Circumference=2 \pi r$

$C=2*8 \pi =16\pi m$

So the distance is:

$16\pi m$

Alfredo ran laps around his track. He had just learned in math about circumference and was wondering what the circumference of his circular track was. He knows that the diameter of his track is 100 feet. What is the circumference of Alfredo's track?

Tap to see back →

The only thing that needs to be known for this question is the equation for circumference which is:

$\pi$

Therefore your answer to this problem is simply

$100\pi$

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

Tap to see back →

To find the perimeter of any object, simply add the length of each side together.

The best answer is:

$\P=s_1+s_2+s_3\=2+2+1\=5$

five inches