Answer:
12.94 units
Explanation:
Perimeter of ∆ABC = AB + BC + AC
✔️Distance between A(1, 1) and B(3, 5):

Where,






AB = 4.47 units
✔️Distance between B(3, 5) and C(5, 1)

Where,






BC = 4.47 units
✔️Distance between A(1, 1) and C(5, 1):
AC = |1 - 5| = 4 units
✅Perimeter of ∆ABC = 4.47 + 4.47 + 4 = 12.94 units