a

b

\sqrt{a.b}

\frac{a+b}{2}

A = (1, 2)
B = (9, 2)
c = Semicircle(A, B)
C = Point(c)
f = Segment(A, B)
g = Segment(B, C)
h = Segment(C, A)
i = OrthogonalLine(C, f)
C_0 = Intersect(i, f)
j = Segment(A, C_0)
k = Segment(C_0, B)
l = Segment(C_0, C)
D_{1} = Midpoint(A, C_0)
E = Midpoint(C_0, B)
F = Midpoint(C_0, C)
C_1 = Midpoint(A, B)
m = OrthogonalLine(C_1, f)
C' = Intersect(c, m, 1)
n = Segment(C_1, C')
G = Midpoint(C', C_1)
p = OrthogonalLine(C, m)