Pi, a mathematical constant denoted by the Greek letter π, is the ratio of a circle's circumference C to its diameter d: π = C/d. The circumference of a circle is, in turn, equal to 2πr, where r is ...

Circles have different angle properties, described by a number of theorems. This is one of two guides on circle theorems, with this guide covering the following: the angle subtended by an arc at the ...

There is Pi all around us, in ways you may not have seen before. If you remember from school, Pi is the ratio of a circle's circumference to its diameter. It is a number that is usually written as ...