2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/3185We derive a simple, fast one-dimensional integral for the equatorial rotation curve of a thin disk with surface density Sigma(R) modeled as a spheroid with axis ratio q. The result is simpler than standard expressions even in the limit of an infinitely thin disk (q-->0).2 pages, no figures, submitted to ApJ LettersAstrophysicstext