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If you know the diameter of a circle you simply divide the diameter by 2 to get the radius. This is because the diameter is twice the length of the radius. For example, if the diameter is 10 divide by two which will give you the answer of 5 for the radius. Half it because: diameter/2 = radius
To answer your question you must have a certin diameter. You must go 2pie times your diameter

The perimeter of a circle is called the circumference. The circumference is the distance around the circle.

The circumference, C, of a circle is given by the formula

where r is the radius of the circle

A radius is half the diameter

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Q: How do you find the radius of a circle if you know the diameter?
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How dou find diameter?

You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.


How do you determine the length of the radius and diameter of a circle?

The answer depends on what information you are given. If you know the circumference, then divide by Pi and that is the diameter. Half of the diameter is the radius. If you don't know anything about the circle, you would need to measure and find the diameter.


When you know the circumference of a circle how do you find the diameter?

If you know the circumference of a circle, you can find the radius by dividing the circumference by the value of Pi (3.14159...)


How do you find the area of a circle that has no diameter?

The circle must have a diameter, so maybe your teacher just didn't tell you the diameter. In order to figure out the question, you need to know some information about the circle. Weather it's the radius, circumference, or diameter. So here's how you find area if you only have each of the three: 1. If you just have the radius, then square the radius. This means multiply radius times radius. Or say the radius is 4. Squaring it is 4 times 4. So once you find out the answer for radius squared, multiply radius squared by pi. (Probably use 3.14 for pi) Then there's your area. 2. If you only have the circumference of a circle, then you need to find the radius. In order to do that, you need to find the diameter. To find the diameter of a circle, you take the circumference and divide it by pi. (3.14) then you have your diameter. Since the radius is half the diameter, divide the diameter by 2. Then, once you find the radius, you may look at step 1 and use those steps to find out the area. Since your question is wondering how to find the area without knowing the diameter, then you can multiply the radius by 2 to find out the diameter. Even though you don't need to know the diameter to find the area. You just do (r times r) times pi (3.14)


How do you find out the circumfrance of a circle?

To find the circumfrance of a circle, you need to multiply 2 times pi, times the circle's radius. If you don't know what that is, you multiply two times pi, and pi equals 3.14, and then multiply that by the radius, which is the measurement of half the circl'e diameter. the diameter is the distance from one side of the circle, to the exact opposite. you measure this with a ruler. HALF the measurement of the diameter is the radius. Example---the diameter of a circle is 20 cm. half the diameter is 10 cm, which is the radius. Multiply 2 times pi[which equals 3.14], times the radius. Good luck!

Related questions

How do you find the diameter of a circle when you know the radius?

Diameter = 2*Radius


How do you find the radius and diameter of the circle if you know the area?

Area of Circle = pi (radius)2 So , using this formula we can find the radius and also the diameter. Diameter = 2(radius)


How do you find the diameter of a circle if you know the radius?

Multiply by two. The diameter is twice the radius.


If you know the diameter of a circle how can you find the radius?

You divide the diameter in half.


How you find radius of a circle if you know the diameter?

Divide your diameter by two


How do you find the center of a circle if you know the radius?

the radius is half of the diameter. and the middle of the circle is half way between this diameter.


How do you get the diameter of a circle?

That depends on what you know. If you know the radius of the circle, double it to get the diameter. If you know the circumference of the circle, divide it by π to get the diameter. If you know the area of the circle, find its square root and divide the result by π to get the radius then multiply by 2 to get the diameter.


How dou find diameter?

You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.You measure it. If you know the radius (of a circle), you multiply it by 2 to get the diameter. If you know the circumference of a circle, you divide by pi to get the diameter.


How do you find the radius if you do not know the diameter?

You can measure it. Otherwise, you certainly have to know SOMETHING about the circle to calculate the radius, usually the diameter, the circumference, or the area. If you don't know anything at all about a circle, you can't find out the radius, either.


How do you find diameter of circle?

To find the diameter you need to know what the radius of the circle which is from the center to the circumference ,the edge, then you times it by two and that's how yo find the diameter


How do you find the radius of a circle if you dont know the circumference?

Well, if you know the diameter you divide that by two to get the radius.


How do you find the radius of the base in a cylinder?

It depends on the values you have. The base of a cylinder is a circle. If you know the circle's diameter, half it to find the radius. If you know the circle's circumference, divide by 2pi to find the radius. If you know the circle's area, divide by pi and take the square root to find the radius.