12cm

8,5cm

15cm

A = (0, -4)
B = (7.795740432025914, -3.960194385621312)
C = (10.682588765458824, -2.2505125558135064)
Vieleck1, c, a, b = Polygon(A, B, C)
D = (0.0013445721602986433, 3.4223645110028715)
d = Segment(D, A)
e = Segment(D, B)
f = Segment(D, C)
E = Point(d)
B' = Rotate(B, 90.0*°, A)
α = Angle(B, A, B')
β = Angle(C, B, A)
γ = Angle(B, D, C)
δ = Angle(D, C, A)