Functions

A function shows how one value varies with respect to another.

For example, the function

$$ volume(radius)=\frac{4}{3}.\pi.radius^3 $$

shows how the volume of a sphere  varies with the radius .

$\pi=3.1415926$ ... is the constant pi .

! Important !
The units of radius and volume are linked. If the radius is in kilometres, the volume is in cubic kilometres. If the radius of a planet is multiplied by 2, the volume is multiplied by $2^3=8$