Question

Prove this theorem indirectly.

Assume you know that the sum of the angles of a triangle equals 180° and a right angle =
90°. Prove that a triangle cannot have two right angles.

Answer 1

Triangles have three sides. Of which, the angles inside add up to 180°. Now if two angles were 90° there would be no third angle. Meaning this object would just be an open shape.