[8] How to design use cases to prove that a triangle is an isosceles triangle

The answer to the questions encountered during the test is as follows:

Assume that the three edges are A, B, and C.
1. Prove that A, B, and C are valid numbers.
2. It is proved that A, B, and C can constitute a triangle.
3. It is proved that the triangle of A, B, and C is an isosceles triangle.

Proves that A, B, and C are valid numbers.
Case 1:
Input Null Value
Case 2:
Input symbol
Case 3:
Enter letters
Case 4:
Input negative number
Case 5:
Input 0
Case 6:
Number of input lengths greater than the specified length
Case 7:
Enter a combination of letters and numbers
Case 8:
Enter valid numbers a, B, c

It is proved that A, B, and C can form a triangle.
Case 9:
Enter a, B, c, and make a + B <c
Case 10:
Enter a, B, c, and B + C <
Case 11:
Enter a, B, c, and make a + C <B
Case 12:
Enter a, B, c, and make a + B = C
Case 13:
Enter a, B, c, and make B + C =
Case 14:
Enter a, B, c, and make a + c = B
Case 15:
Enter a, B, c, make a + B> C, A + C> B and B + C>

It is proved that the triangle of A, B, and C is an isosceles triangle.
Case 16:
Enter a, B, c, and a = B = C
Case 17:
Enter a, B, c, and make a = c = B
Case 18:
Enter a, B, c, and make a = B = C
Case 19:
Enter a, B, c, and a = c = B
Case 20:
Enter a, B, c, and make B = C =a