Q&A for How to Find the Circumference and Area of a Circle

Divide the area by pi; that gives you r ². Find the square root; that gives you r. Double it; that gives you the diameter. Multiply by pi; that gives you the circumference.

Pi x diameter = Pi x (2 x radius) = Circumference So: Radius = Circumference/(2xPi) Once you have the radius, use this formula: Area = Pi x radius^2

Divide the area by pi. That's the square of the radius. Find the square root. That's the radius. Double it. That's the diameter. Multiply by pi. That's the circumference.

Divide the area by pi to get the square of the radius. Take the square root to get the radius. Double it to get the diameter. Multiply by pi to get the circumference.

The diameter is twice the radius.

Pi is irrational because its value cannot be exactly expressed as a fraction (that is, a ratio of integers). 22/7 is often used as an expression of pi, but it is only an approximation of the true value. Even 3.14159 is only an approximation of pi's value (which is actually an apparently endless decimal number).

Remember these; a=2πr, and C=πr². First you need to find the square root of the circumference, and then divide that by π. This will be the radius of the circle, and then you simply find the area using the formula. Using algebraic rulings, you can also do this backwards, from the area to the circumference.

If the circle is touching the sides of the square, that means that the diameter of the circle equals the length of the square side. Just multiply the diameter by pi, and you have your circumference!

Treat that radius as if it were an actual number. To find the circumference, you double the radius and multiply by pi. To find the area, you square the radius and multiply by pi.

Divide the area by pi: that's the square of the radius. Find the square root: that's the radius. Double it: that's the diameter.

The circumference of a circle is length rather than area, so it would just be meters.

The radius, half the diameter, would be 18. You would square 18 to get 324. After that, multiply by pi.

Centimeters are a unit of measurement. You do the same math, and it is simply in the centimeters unit.

Work out the radius by rearranging the formula A = Pi x r^2 to get r = sqrt Pi / sqrt A. Then, double the radius by multiplying it by two and use the formula C = Pi x d.

The area increases by the square of 8%, or 64%.

Divide the area by pi. Then find the square root of that quotient.

No. It's never necessary to square the circumference. If you're looking for the area, you would square the radius and multiply by pi.

If you know the circle's radius, double it. If you know its circumference, divide it by pi. If you know its area, divide it by pi, then find the square root of that quotient. If you do not know the circle's radius, area or circumference, you cannot find its diameter.

First treat it as if it were a full circle. Find its circumference. Then divide that by 2.

Dividing the area by pi gives 49.02, which is the square of the radius. So the radius is almost exactly 7, and the diameter is 14. Multiply the diameter by pi to get the circumference: 43.98 square units.