parametric equations

of: a given equation (e.g. of the standard equation of a conic section)

are: equations in which each of the variables in the given equation is expressed in terms of one or more new variables known as parameters.

are exemplified: by the parametric equations of a circle:

where is the parameter,

since using the identity = 1 to eliminate the parameters leads to the standard equation of the circle [M2.3, M4.3]