A = (1.98, 4.2)
B = (0.78, 2.06)
f = Line(A, B)
C = (2.54, 2.88)
g = Line(B, C)
h = Line(A, C)
D = Point(g)
E = Point(h)
i = Line(D, E)
F = Intersect(f, i)
G = g(A, F, D, C)
H = g(A, B, D, E)
I = g(F, B, E, C)
a = AreCollinear(G, H, I)

Tool: f
工具1[ <点>, <点>, <点>, <点> ]
Input: A, B, C, D
Output: I

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)

Tool: g
工具2[ <点>, <点>, <点>, <点> ]
Input: A, B, C, D
Output: L

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)