A

B 

C

a

b

c

h

p

q

A = (2, -5)
B = (18, -5)
f = Segment(A, B)
c = Semicircle(A, B)
C = Point(c)
g = Segment(A, C)
h = Segment(C, B)
α = Angle(B, A, C)
β = Angle(C, B, A)
γ = Angle(A, C, B)
i = OrthogonalLine(C, f)
D = Point(i)
j = Segment(C, D)