o)+Diameter

This page gives you all you need to know about diameter and how to figure it out.

How do you find the diameter of a circle?

Posted by **96carolina**: We don't exactly understand how to find the radius of a circle and the formula is confusing for us. Is there a simpler way to learn it?

Posted by: **CoconutCracker** To find the diameter of the circle all you go to do is multiply the radius by 2 to get the diameter.If they dont give you the radius all you got to do is measure the circle from one point to another using a ruler.The line must be a straight line.

Posted by : **DummyDerrick**

You can find the diameter of a circle by dividing the circumference by 2.

For example, if the circumference of a circle is 6, the diameter would be 3...

Hope that helps!

posted by: **smokey-dice1212** the operation that derrick used is not for finding the radius of a circle, it is used to find the area of a circle.

Posted by: **CoconutCracker** How can you find radius when you are multiplying the radius derrick?

Posted by: **Craxyjosh** and **Partykala**

A circle is the set of all points in a plane at a fixed distance, called the radius, from a given point, the center.
 * Circle Tutorial ||
 * || **Circle Definition:**

Area of Circle = πr² Diameter of Circle = 2r Circumference of Circle = 2πr = πd Area of Sector = πr²(θ/360) where r = radius
 * Circle Formula**:

Radius: a straight line extending from the center of a circle or sphere to the circumference or surface: //The radius of a circle is half the diameter.//

Diameter: a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.

Circumference: the length.

**Circle Image/Diagram**
 * [[image:http://www.easycalculation.com/area/images/big-circle.gif]]Circle Example**:

Case 1: Find the area, diameter and circumference of a circle with the given radius 3.

__Step 1:__ Find the area. Area = πr² = 3.14 * 3² = 3.14 * 9 = 28.26.

__Step 2:__ Find the diameter. Diameter = 2r = 2 * 3 = 6.

__Step 3:__ Find the circumference. Circumference = πd = 3.14 * 6 = 18.84.

Case 2: Find the area of sector with the given radius 3 and then a 30.

__Step 1:__ Find the area. Area =πr²(θ/360) = 3.14 * 3² * (30/360) = 3.14 * 9 * 0.083 = 2.35.

The above example will clearly illustrates how to calculate the area, diameter and circumference of a circle, area of sector manually.

Posted by: **SalinaKung** To find the diameter of a circle, you first have to find the circumference of the circle. Then you divide the cicumference of the circle by pi (3.14), and you get the answer. For example, if the circumference of a circle was 15.7 cm, you would divide 15.7 by 3.14, and you would get the answer. The answer would be 5 cm.

Posted by: **SalinaKung** If you know the diameter of a circle and you wanted to find the circumference of the circle, you would multiply the diameter by pi (3.14). Then you will end up with the answer. For example, if the diameter of a circle was 10 cm and you wanted to find the cicumference of the circle, you would multiply 10 by 3.14. Then you will get the answer, 31.40 cm.

Posted by: **SalinaKung** How can you find the area of a circle that has a radius of 4 cm?

__the answer to salina kungs question: posted by :__**smokey-dice1212**

you have to do it on a calculator -> pi multiplied by the square of the radius,

so in this case = pi multiplied by 16 = 50.26cm squared

A = πr² A = π x (4 cm)² A = 16 x π cm² A ≈ 50.265 cm² ||  ||