Trigonometry and precalculus
Parametric equations and polar coordinates
An alternative to Cartesian coordinates.
Parametric equations
Here we will explore representing our x's and y's in terms of a third variable or parameter (often 't'). Not only can we describe new things, but it can be super useful for describing things like particle motion in physics.
Polar coordinates
Feel that Cartesian coordinates are too "square". That they bias us towards lines and away from cool spirally things. Well polar coordinates be just what you need!