Answer:
3. D) 26, 7, 31
4. B) 6, 34, 27
Explanation:
Both #3 and #4 use the same strategy: the two shorter sides' sum has to be greater than the longer side.
#3:
2 + 8 is 10, which is less than 13. So A wouldn't form a triangle.
12 + 22 is 34, which is the length of the longer side. So B wouldn't form a triangle either.
14 + 18 is 32, which is less than 40. So C wouldn't form a triangle.
7 + 26 is 33, which is greater than 31. So D would form a triangle.
D. 26, 7, and 31 are the only lengths of the ones shown that form a triangle.
#4:
17 + 18 is 35, which is greater than 19. So A would form a triangle.
11 + 22 is 33, which is greater than 25. So C would also form a triangle.
5 + 18 is 23, which is greater than 20. So D would form a triangle.
6 + 27 is 33, which is less than 34. So B wouldn't form a triangle.
B. 6, 34, and 27 are the only lengths of the ones shown that don't form a triangle.