An obtuse triangle has 1 obtuse angle. The rest of them are acute. The equation a2 + b2 < c2 can be used to prove that triangles are obtuse by using their sides. This article is a stub. You can help Math Wiki by expanding it.vte Retrieved from "https://math.wikia.org/wiki/Obtuse_triangle?oldid=12554" Categories: Stubs Geometry Triangles Euclidean plane geometry Geometric shapes Community content is available under CC-BY-SA unless otherwise noted.