ABSTRACT
Certain mathematical relationships can be expressed more simply by stating both x and y in terms of a third variable, say, θ. By doing this, subsequent work is frequently simplified. When both x and y are expressed in terms of the same variable, this variable is called a parameter. The equation of any point on a circle, centre at x = 0 and y = 0, and of radius r, is given by x 2 + y 2 = r 2.
