The radius of a circle or a sphere is the distance between the center and the edge. The radius can be used to calculate a circle's diameter, area and circumference. Likewise, a sphere's volume is ...

So you have a circle. What is the area of that circle? Surely everyone remembers that the area of a circle is: Where Pi (π) is of course the number and r is the radius of the circle. Where does this ...

A circle is a shape where every point at its edge is the same distance from the centre. A circular shape or object is one that is in the form of a circle. How many of these circular objects can you ...