Can a right triangle also be obtuse? explain your reasoning. yes; by the exterior angle theorem, if one of the exterior angles is obtuse, then it is possible for one of the two nonadjacent interior angles to be obtuse. yes; a right angle measures 90∘∘. by the corollary to the triangle sum theorem, the other two angles are complementary. so, one of those angles can be obtuse as long as the sum of the two angles is 90∘∘. no; by the corollary to the triangle sum theorem, the angles in a right triangle that are not right angles are acute and complementary. no; by the exterior angle theorem, if one of the exterior angles is obtuse, the two nonadjacent interior angles will each have half the measure of the exterior angle, so they will both be ac