1. Triangles can be classified based on their sides as isosceles, scalene, or equilateral. The sum of the interior angles of any triangle is always 180 degrees. 2. The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles. 3. True or false questions about triangle properties include: if two angles are congruent then the third must be; each angle of an equiangular triangle is 60 degrees; a triangle can have at most one right or obtuse angle.