Why can't two obtuse angles be supplementary? Geometry Angles and Intersecting Lines Angles with Triangles and Polygons 1 Answer Konstantinos Michailidis Nov 23, 2015 Because an obtuse angle is greater than #90^o# so their sum is going to be greater than #180^o# which is the total for supplementary angles. Answer link Related questions How do you classify the triangle given 2 cm, 2 cm, 2 cm? The angles of a triangle have the ratio 3:2:1. What is the measure of the smallest angle? Is an equilateral triangle is sometimes, never or always an isosceles triangle? What is an isosceles triangle? How do I prove that these are the vertices of an isosceles triangle: (-3,0), (0,4), (3,0)? Is it possible to have an isosceles scalene triangle? How would you show that a triangle with vertices (13,-2), (9,-8), (5,-2) is isosceles? An isosceles right triangle has legs that are each 4cm. What is the length of the hypotenuse? Triangle XYZ is isosceles. The base angles, angle X and angle Y, are four times the measure of... What is the isosceles triangle theorem? See all questions in Angles with Triangles and Polygons Impact of this question 4224 views around the world You can reuse this answer Creative Commons License