From the centre to the edge is the radius, from the edge to the edge all the way across is the diameter. It's simples. Look you do this, I gotta go out. Five pizza. Remember. Good boy. VO ...

To work out the area of a circle: Find the value of the radius. If the diameter is given, this must be halved. Substitute the value of the radius into the formula for the area of a circle.

Scientists have calculated the value of pi to one hundred trillion digits, but you don't have to be a mathematician to ...

The diameter is the length across the widest part of the circular base. Record your measurements on a separate piece of paper. 3. Assume that a grain of sand is basically a sphere, with a radius ...