They don't...
Pi
pi = circumference divided by diameter
C = 2*radius*pi
Because area of any circle = pi*radius2
This is simply 3.14, or pi.
it has anything to do with circles
The cicumference of any circle divided by its diameter is aways equal to pi.
The Greek letter Pi (Ï€) is the equivalent to the English/Latin letter P
One definition of pi is the ratio of the circumference, C, of a circle to its diameter.,d. pi=C/d The area of a circle is (pi)r2 or (pi)d2/4 where r is the radius.
It's a number - used in problems involving geometry.
To express a quantity in terms of pi, you need to relate it to a circular measurement, such as the circumference or area of a circle. For example, if you have the circumference of a circle, you can use the formula ( C = 2\pi r ), where ( r ) is the radius, to express the circumference as a multiple of pi. Similarly, for the area, use ( A = \pi r^2 ) to express the area in terms of pi. Simply factor out pi from the equation to achieve the desired expression.
The number pi is the ratio of the circumference and the diameter of a circle. In Euclidian ("flat") geometry, this ratio is the same for all circles. The number pi is approximately 3.1416. It also has many other uses in mathematics and physics, not all of which have an obvious relation to a circle or sphere.