The exterior angle of a triangle is always greater than either
of its corresponding interior angles:
Two important things to remember is that if one side of a
triangle is longer than another side (compare BC and AB in the
triangle below BC > AB) then the angle opposite of the longer
side is always greater than the angle opposite (A > B) of the
shorter side. Likewise if one angle is greater than another angle
(A > B) then the side opposite of the greater angle is always
longer than the side opposite the lesser angle (BC > AB).
The sum of the lengths of any two sides in a triangle is always
greater than the length of the third side:
Video lesson: List the sides of the triangle in
the order from shortest to longest.