Answer: 11.6 units.
Explanation:
1. Plot the points as you can see in the graph attached.
2. As you can see, the lenght TA is 3 units.
3. Apply the formula for calculate the distance between two points, to calculate the length TP and TA. The formula is:

4. Therefore, you have:


5. The perimeter is the sum of the the lenght of each side, therefore:

6. To the nearest tenth unit:
