Final answer:
The possible lengths for the third side, x, of a triangle can be found using the triangle inequality theorem. The correct answer is (c) 14.
Step-by-step explanation:
The possible lengths for the third side, x, of a triangle can be found using the triangle inequality theorem. According to the theorem, the sum of the lengths of any two sides of a triangle must be greater than the length of the third side.
In this case, the two given sides have lengths 5 and 18, so the possible lengths for the third side, x, are:
x > 18 - 5 = 13
5 + x > 18
Therefore, the correct answer is (c) 14, as 14 satisfies both inequalities.