Parametric Equations

Throw a ball and it arcs through the air. Its height depends on time, and so does its horizontal distance — but they're driven by a THIRD variable, time t, not by each other. To describe motion, you don't graph y as a function of x; you graph BOTH as functions of t. That's a parametric equation: x = x(t), y = y(t), with t as the hidden conductor. It's how physics, animation, and robotics describe anything that moves through space over time.