### Essential Concepts

- Parametric equations provide a convenient way to describe a curve. A parameter can represent time or some other meaningful quantity.
- It is often possible to eliminate the parameter in a parameterized curve to obtain a function or relation describing that curve.
- There is always more than one way to parameterize a curve.
- Parametric equations can describe complicated curves that are difficult or perhaps impossible to describe using rectangular coordinates.

## Glossary

- cusp
- a pointed end or part where two curves meet

- cycloid
- the curve traced by a point on the rim of a circular wheel as the wheel rolls along a straight line without slippage

- orientation
- the direction that a point moves on a graph as the parameter increases

- parameter
- an independent variable that both
*x*and*y*depend on in a parametric curve; usually represented by the variable*t*

- parametric curve
- the graph of the parametric equations [latex]x\left(t\right)[/latex] and [latex]y\left(t\right)[/latex] over an interval [latex]a\le t\le b[/latex] combined with the equations

- parametric equations
- the equations [latex]x=x\left(t\right)[/latex] and [latex]y=y\left(t\right)[/latex] that define a parametric curve

- parameterization of a curve
- rewriting the equation of a curve defined by a function [latex]y=f\left(x\right)[/latex] as parametric equations