Pi

Pi is a characteristic of circles.

It is defined as the ratio between the circumference and the diameter of any given circle; this ratio is the same regardless of the size of the circle.

If you draw a circle (of any size) and measure circumference by the measured diameter.

Depending on the accuracy of your drawing and measurement, pi is about 3.1415927...*.

Since pi is the same for all circles, you can calculate (instead of measure) the circumference of any circle by simply multiplying the diameter with this constant

Definition of pi :


pi = circumferencce /diameter


Note : 22/7 is just an approximation of what pi really is.

Since the diameter is twice the radius, thus

Pi = circumference /2. radius

Hence we arrive at the following formula for the circumference of a circle:

circumference = pi . diameter
= pi . 2 . radius