Arc length is a fraction of circumference. Area of a sector is a fractions of the area of a circle. Both can be calculated using the angle at the centre and the diameter or radius. Practice circle ...

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 ...

The shortest distance between two points is a straight line. This is one of the basic principles of Euclidean geometry. But we live on a spherical Earth, so we cannot travel the straight line path ...

Get a fresh, colourful angle on the basics of geometry! What are angles? Do you know the difference between a triangle and a quadrilateral? These videos on the basics of geometry will help you ...

In 1973, Alexander Thom, et al surveyed Stonehenge and proposed a geometry based on circles and ellipses for the layout of its various features. His premise is that circles and ellipses have their ...

Three mathematicians show, for the first time, how to form a square with the same area as a circle by cutting them into interchangeable pieces that can be visualized. Around 450 BCE, Anaxagoras of ...