Final answer:
The length of the third side must be less than 20 units.
Step-by-step explanation:
A triangle has three sides, and the sum of the lengths of any two sides must be greater than the length of the third side. In this case, the lengths given are 8 and 12 units. To find the range of possible lengths for the third side, we can use the triangle inequality theorem. If we let x represent the length of the third side, the inequality becomes:
8 + 12 > x
Simplifying the inequality, we have:
20 > x
Therefore, the length of the third side must be less than 20 units. In conclusion, the third side of the triangle must have a length less than 20 units.