Arc length measures the exact distance along a curve by adding infinitely many tiny straight-line distances. This Woody Calculus lesson derives the formula, explains the ds triangle, and solves the classic hard arc length example step by step.
Improper integrals are Calculus 2 limit problems in disguise. This Woody Calculus lesson teaches how to handle infinite intervals, vertical asymptotes, bad points inside an interval, p-integrals, comparison tests, convergence, and divergence with a clear step-by-step system.

