Considering this is a triangle you just need to take the distance from each point.
B to C , X ,-3 -3 = -6 Y, 3 -5 = -2 = -6,2 =-6² + 2² = 36 + 4 = √40 Distance from B to C
C to D , 3 - -1 = 4 , 5 - 0 = 5 , => 16 + 25 = √41
D to B , -1 --3 = -2, 0 - -3 = 3 , = > 4 + 9 = √13
Perimete = √40 + √41 +√13