The perimeter of a circle is called the circumference. The shortest distance from the centre to the circumference is called the radius. The line across the centre of a circle is the diameter, this is ...

The circumference of a circle = \(\pi d\) or \(2\pi r\). Look at the sector of the circle shown below. To calculate the length of the arc, we need to know what fraction of the circle is shown. To do ...

Introduction If you wanted to measure the circumference of Earth, how long would your tape measure have to be? Would you need to walk the whole way around the world to find the answer? Do you think ...