The arc length of a curve is the distance along the curve between two points. It measures how long the curve is.
Equations that express variables in terms of parameters. They are often used to describe curves or paths in space.
A line that touches a curve at only one point and has the same slope as the curve at that point.
The rate at which a function changes with respect to its input variable. It represents the slope of a tangent line to a curve at any given point.