Answer:
the desired range is 2 < t < 12.
Step-by-step explanation:
If the third side is 12 (the sum of 5 and 7), we don't really have a triangle, since the 5-unit and 7-unit sides add up to 12 and lie on the third side (of length 12).
Since triangle ABC is acute, all its angles are between 0 and 90 degrees. So the third side can be 12 but not greater. The smallest possible length of the third side is 2, since 5 + 2 = 7.
Thus, the desired range is 2 < t < 12.
