1 Case 1: Invalid 2 Case 2: Isosceles 3 Case 3: Invalid 4 Case 4: Invalid 5 Case 5: Invalid 6 Case 6: Invalid 7 Case 7: Invalid 8 Case 8: Scalene 9 Case 9: Invalid 10 Case 10: Scalene 11 Case 11: Invalid 12 Case 12: Scalene 13 Case 13: Invalid 14 Case 14: Invalid 15 Case 15: Invalid 16 Case 16: Scalene 17 Case 17: Invalid 18 Case 18: Invalid 19 Case 19: Invalid 20 Case 20: Invalid