Radii

A radius is a line segment that connects the center of a circle or sphere to any point on its edge or surface. It measures the distance from the middle point to the outer edge. In a circle, all radii are equal in length, serving as a fundamental way to describe the size of the circle. For example, if you think of a wheel, the radius is the distance from the hub (center) to the rim (edge). The radius is key in calculating other properties of circles and spheres, like area and volume.