...Whether taking this as a class of its own, or as part of some other class, you will want to know your unit circle, and be able to prove various trig identities. Learn how to graph polar coordinates and use formulas like de Moivre's formula. The basics of Trigonometry tend to be taught in Geometry and/or Algebra II, but you will need it throughout Precalculus, and Calculus. (read more)