The diameter of a circle is a line segment that passes through the center of the circle and connects two most distant between a point lying on the circumference. The length of this segment is also called a diameter of the circle. The radius is half the diameter of a circle, so if you know the diameter of this circleto find its radius by dividing it in half. R = D/2 where D is the diameter of the circle.
The length of the curve, forming a circle on a plane is the length of the circumference. If the known length of a circle you can use the formula: R = L/2?, where L is the length of the circle, ? is a constant equal 3,14159... Constant ? equal to the ratio of the length of the circumference to the diameter, this value is the same for all circles.
A circle is a geometric figure that represents the portion of the plane bounded curve is a circle. If you know the area of a circle, find the radius of a circle from the following formula: R = v(S/?), where v is the square root, S – the area of a circle.