(Δ)

O = Intersect(xAxis, yAxis)
c = Circle(O, 50)
G = Intersect(c, xAxis, 2)
H = Intersect(c, yAxis, 2)
d = CircleArc(O, G, H)
A = Point(d)
a = OrthogonalLine(A, xAxis)
b = OrthogonalLine(A, yAxis)
B = Intersect(c, b, 2)
e = OrthogonalLine(B, xAxis)
C = Intersect(c, e, 2)
D = Intersect(c, a, 1)
poly1, AB, BC, c_1, d_1 = Polygon(A, B, C, D)
M: (AB, poly1)
f = Segment(H, O)
g = Segment(O, G)
α = Angle(G, O, H)