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you multiply 3.14 then the radius by the radius then you divide your answer by 2. Example: radius= 30

3.14 times 30 times 30= 30 times 30= 900 times 3.14= 2,826

now you divide it by 2

2,826 divided by 2= 1,413

so then.....

the area= 1,413

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Q: How do you find the area of a circle if you know the radius?
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How do you find the radius of a circle if you don't have the area?

If you do not have the area, what do you have? The radius is half the diamiter The radius is PieR2 Worked backwards if you know the circumfrence.


How do you calculate the area of a circle when you know radius?

a=3.14xradius squared


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)


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...)


What is the mathematical formula for finding the radius of a circle?

To calculate this you will need the diameter of the circle. The formula is: diameter/2*pi If you don't know the diameter you can also use the area of the circle: Sqrt(Area/pi) = radius

Related questions

When you know the radius of a circle how can you find the area?

Area of a circle = pi*radius2


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

Radius = +sqrt(Area/pi)


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 radius if you know the area of a circle?

Radius is the square root of (area divided by pi).


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.


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

Area of a circle equals pi r2 Therefore the radius of a circle equals the square root of (area divided by pi).


What is the required piece of information tho find the area of a circle?

The only piece of information required to find the area of a circle is the radius of the circle. Once you know the radius of the circle, the area is simply the radius squared multiplied by pi (approximately 3.14).


How do you find the area of a circle if you only know its circumference?

Divide its circumference by 2*pi which will give the radius of the circle. Area of the circle then is pi*radius squared


How do you find the radius of a circle if you don't have the area?

If you do not have the area, what do you have? The radius is half the diamiter The radius is PieR2 Worked backwards if you know the circumfrence.


How do you find the circumference of a circle when you know the area?

OK, SO to find the area of a circle, you find the radius (half of the diameter), and fit it into the equation πr2=A where r equals radius and A = area. The perimeter of a circle is π multiplied by the diameter. π is ≈ 3.1415296.


Does the radius affect the area of a circle?

Yes the radius does affect the area of a circle. In fact to find the area of a circle people need to know the radius. The radius is half way between the middle of a circle to any of it's edges. The formula for the area of a circle ispi*radius squaredYou must first find the square of the radius and multiply it by pi(3.14.) For more help go to Wikipedia.com and type circle.


How do you work out the difference of the area of a circle and the area of a square when the radius of the circle is 6cm and the side of length of the square is 12cm?

Do you know how to find the area of a circle when you know the radius ? Good! Do that. Do you know how to find the area of a square when you know the length of the side ? Good! Do that. Now you have two numbers ... the area of the circle and the area of the square. The problem wants you to find the difference of these two numbers. Do you know how to use subtraction to find the difference of two numbers ? Good! Do that.