Carcass wrote:
OE
Any side x of a triangle must be greater than the difference between the lengths of the two other sides, and less than the sum of the two other sides. In this case, the third side must be between (12 - 5) = 7 inches, and (12 + 5) = 17 inches. Therefore, 7 < x < 17. Only 17.5 inches is outside this range.
The question says the side is length 3, not length 5.