What is the arclength between two points on a curve? How does it differ from the distance?

1 Answer
Nov 8, 2015

The distance is the arc length on a straight line. The arc length is the distance along the arc.

Explanation:

Example

For the points (-1,0)(1,0) and (1,0)(1,0),

the distance between the points (the length of the straight line joining them) is 22.

The length of the arc on the unit circle: x^2+y^2=1x2+y2=1 is half the circumference, so it is piπ. (More completely, the lengths of both the upper and lower arcs are piπ.)