f

工具1[ <点>, <点>, <点>, <点> ]

g

工具2[ <点>, <点>, <点>, <点> ]

f = Segment(A, B)
g = Segment(B, C)
h = Segment(C, D)
i = Segment(D, A)
E = Midpoint(f)
F = Midpoint(g)
G = Midpoint(h)
H = Midpoint(i)
c = Circle(E, A)
d = Circle(G, D)
e = Circle(F, B)
k = Circle(H, A)
eq1: LeftSide[c] - RightSide[c] = LeftSide[d] - RightSide[d]
eq2: LeftSide[e] - RightSide[e] = LeftSide[k] - RightSide[k]
I = Intersect(eq1, eq2)
E = f(A, B, C, D)
J = f(A, B, D, C)
K = f(A, C, B, D)
p = Circle(E, J, K)
L = Center(p)