Parametric Curves and Motion — Cheat sheet

Choose “Save as PDF” in the print dialog.
On this page

Core rule

dydx=y′x′,d2ydx2=(y′/x′)′x′,L=∫x′2+y′2 dt.\frac{dy}{dx}=\frac{y'}{x'},\quad \frac{d^2y}{dx^2}=\frac{(y'/x')'}{x'},\quad L=\int\sqrt{x'^2+y'^2}\,dt.

Watch for

Slope formulas require x′≠0x'\ne0. Distance counts repeated traversal, while displacement depends only on endpoints.