You are given a program that accepts 3 numbers as input (length of sides of triangle). The program output is taken from the set {Equilateral, Isosceles, Scalene, Invalid}. The program is supposed to choose the most specific descriptor. (i.e 2,2,2 should return Equilateral and 2,2,1 should return Isosceles.) You do not have the source code for this program.

a) Is this a white box or black box testing? Explain.

b) Name at least one advantage and one disadvantage of each approach.

c) Why are both approaches necessary?