Triangles

SSS (Side-Side-Side), SAS (Side-Angle-Side), ASA (Angle-Side-Angle), RHS (Right angle-Hypotenuse-Side)

Valid congruence tests are: SSS (all three sides equal), SAS (two sides and included angle), ASA (two angles and included side), and RHS (for right triangles). AAA only shows similarity, not congruence, as triangles can have same angles but different sizes.

True

This is the exterior angle theorem property. An exterior angle equals the sum of its two remote interior angles, so it must be greater than either individual remote interior angle. If exterior angle = angle1 + angle2, then exterior angle > angle1 and exterior angle > angle2.

Equilateral triangle - All angles are 60°

Equilateral triangles have all sides equal, so all angles are 60°. Isosceles triangles have two equal sides, so two base angles are equal. Right triangles have one 90° angle. Scalene triangles have all sides different, so all angles are different.