Answer:
24.1 is a possibility for the perimeter
Explanation:
The third side between 12+0.5 and 12-0.5, or 12.5 and 11.5.
The third side is between 11.5 and 12.5.
Simce it isn't isosceles third side can't be 12.
So it's asking you to choose a number between 11.5 and 12.5 with the exclusiion of 12 for the third side measurement in meters.
So let's choose 11.6.
So the perimeter is just the sum of all side measurements.
11.6+12+0.5
11.6+0.5+12
12.1+12
24.1
24.1 is a possibility for the perimeter