Required Perimeter = AB + BC + CA
AB = sqrt((5 - (-1))^2 + (-1 - 1)^2) = sqrt(6^2 + (-2)^2) = sqrt(36 + 4) = sqrt(40) = 6.3
BC = sqrt((-1 - 0)^2 + (1 - (-3))^2) = sqrt((-1)^2 + 4^2) = sqrt(1 + 16) = sqrt(17) = 4.1
CA = sqrt((0 - 5)^2 + (-3 - (-1))^2) = sqrt((-5)^2 + (-2)^2) = sqrt(25 + 4) = sqrt(29) = 5.4
Perimeter = 6.3 + 4.1 + 5.4 = 15.8 units