# Defining curves with parametric equations - Parametric Equations and Polar Coordinates

### Defining curves with parametric equations

We have focused a lot on Cartesian equations, so it is now time to focus on Parametric Equations. In this section, we will learn that parametric equations are two functions, x and y, which are in terms of t, or theta. We denote the variables to be parameters. Then we will learn how to sketch these parametric curves. After, we will analyze how to convert a parametric equation to a Cartesian equation. This is known as eliminating the parameter. Sadly, not all parametric equations can be converted to Cartesian in a nice way. This is especially true for parametric equations with sine and cosine. Therefore, we will introduce another way of eliminating the parameter, which involves using trigonometric identities.