**The diameter of a circle can be calculated using the formula d = 2r, where "d" indicates the diameter and "r" denotes the radius of the circle.** In terms of circumference, the diameter can be computed using the equation d = c/pi, where "c" represents the circumference and pi is approximately equivalent to 3.142. If the area of the circle is given, the formula d = sqrt (4a/pi) can also be used to solve for the diameter, where "a" denotes the area.

A circle is a two-dimensional geometric figure where all points are equidistant from the center. It is characterized by its radius, diameter, circumference and area. Radius measures the length of the line from the center point to the edge. A diameter pertains to the distance between two points on the circle connected by a line passing through the center point. The circumference measures the length of the rounded perimeter of the circle while area refers to the enclosed region within the circle.

A diameter is bisected into two radii by its midpoint, thus it can be computed by multiplying the radius by 2. For example, a circle having a radius of 4 inches has a diameter equal to 8 inches. Given a circumference of 10 inches, the diameter of the circle is approximately 3.18 inches. A circle with an area of 15 square inches has a diameter approximately equal to 4.37 inches.