First watch the demonstration. Then you can change the lengths of the triangle with the sliders a, b and c. Look whats happening and answer the following questions: What happens, when - the sum of 1 pair of sides exactly equals the measure of a 3rd side? - the sum of 1 pair of sides is less than the measure of a 3rd side? - the sum of 1 pair of sides is more than the measure of a 3rd side?