1. By definition, the altitude of a triangle forms a right angle with the side opposite the top of the triangle. 2. Since there is a right angle formed, two right triangles are created. 3. Thus altitude is a leg of these right triangles, while the sides containing the vertex of the altitude are each a hypotenuse. 4. The hypotenuse is always longer than either leg of a right triangle. 5. Thus, the sides containing the vertex of the altitude are longer than the altitude.