1) To find out wich three numbers can be the lengths of the legs of a triangle, we must use the Triangle Inequality
|a -b| < c < a +b
2) So examining 12, 17 and 26
|a -b| < c < a +b
|12-17| < 26 < 12 +17
5 < 26 < 29 True
12, 20, 29
|12 -20| < 29 < 20 +12
8 < 29 < 32 True
7, 20, 25
| 7 -20| < 25 < 25 +7
13 < 25 < 32 True
7, 16, 24
|7 -16 | < 24 < 7 +26
9< 24 < 33 False
2) So the set of numbers that could n