Constants and Variables

A constant is a quantity that stays unchanged throughout a mathematical process; a variable is one that changes. A variable is independent if it can take any value freely; it is dependent if its value is determined by other variable(s).

Examples.

• Area of a triangle $A=\tfrac12bh$: here $\tfrac12$ is a constant; $b,h$ are independent variables and $A$ is dependent on them.
• Area of a rectangle $A=\ell b$; area of a circle $A=\pi r^2$ ($\pi$ constant); volume of a cuboid $V=\ell bh$. In each, the geometric measurements ($\ell,b,h,r$) are independent and the computed quantity ($A$ or $V$) is dependent. …