2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/114867Several different but equivalent forms of the spherical black hole (Schwarzschild) are known, as well as several derivations. Here a novel form is derived through the power of the action formalism. The method generalizes to any spherical black hole or brane, and the charged hole case (Reissner-Nordstrom) is worked out in detail.11 pages, 1 figure. v2: see "Note added" at end of paper for clarifications and added reference. v3: added referenceGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext