Here the Greek letter p represents the constant ratio of the circumference of any circle to its diameter approximately equal to 314159. It can be determined easily using a formula A pr2 Pi r-squared where r is the radius of the circle. While this might seem impossible it is doable if you divide the circle into thinner and thinner slices until parts become infinitesimally small and can form an exact rectangle.
The area of a circle calculator helps you compute the surface of a circle given a diameter or radiusOur tool works both ways - no matter if youre looking for an area to radius calculator or a radius to the area one youve found the right place.
Visual on the figure below. By using the surface area of a circle formula to find area find two times the radius and multiply the obtained value with pi constant 314 then again multiply the value you have got with 4. Mathematically we can imagine a ring with radius x and thickness d x anywhere in the circle having the same center as the circle calculate its area and then sum up integrate it from x 0 to x R. Just plug that value into the formula for the area of a circle and solve.