In order to find the area of a circle, we must know the formula that will give us the appropriate answer. The area of a circle is , where r is the radius. 

However, the problem doesn't give us a value for the radius. The only value provided is the diameter. The formula for diameter is , where d is diameter and r is radius. Using this relationship will help us find r so we can solve for the area. 

Now that we know that value of r, the area can be solved for. 

In order to find the area of a circle, we must know the formula that will give us the appropriate answer. The area of a circle is , where r is the radius. 

Since the problem provides the value of the radius, we just need to substitute in the value for r in order to solve for area 

The formula for the area of a circle is

with  standing for radius.

In this problem, however, you are given the diameter, not the radius. You therefore need to solve for the radius first. This is simple. The diameter is twice the length of the radius, so if the diameter is , the radius is . .

Once you have the radius, you can plug it into the formula for the area of a circle, and solve. 

So, the area of the circle is .

You and your friends are ordering pizza for your Friday night Mathathon. You decide to order three pizzas, each 16" in diameter. Find the area of each pizza to the nearest tenth.

First, let's convert our diameter to radius:

Next, use the following formula to solve for Area.

So, our answer is:

A  arc of the circle is one fourth of the circle, so the length  of the arc is 

,

where is its circumference.

Since , substitute as follows:

Multiply both sides by 4:

The radius of a circle is its circumference divided by , so

Substitute this for  in the formula 

to get

,

the correct choice.

First we need to recall that the formula for area of a circle is 

Where  is radius and  is 3.14

The circe we are working with has a diameter of 12. The diameter is twice the length of the radius, so to find the radius we cut it in half, and we get 6cm.

Now we can plug our radius and pi into our equation and solve for the area

Following order of operations, first we need to address the exponent. Any number to the second power (squared) is that number times itself one time (in this case it is 6x6)

Next we multiply

Since we multiplied two terms whose units are in cm, our answer is in centimeters squared.

Find the area of a circle given that the distance from its center to its edge is 6.25 meters.

Area of a circle is given by:

We know that our radius is 6.25 m, given that this is the distance from the center to the edge.

Plug in and solve.

So our answer is

Recall the formula for the area of a circle

Here, r is the radius, which in this case is 5

The formula to calculate the area of a circle is defined as:

The diameter is twice the length of the radius, or . To find the radius, we must divide the diameter by 2.

Now, we plug in  into the formula to find the area of the circle:

The circumference of the circle is the sum of the lengths of the arcs, which is

.

The white sector has degree measure

.

The radius of the circle can be found using the circumference formula, setting :

The area of the white sector is therefore

.