Reflecting three times
Author: R. Albers

Move H so that the blue triangle meets the green one.
Then move E (e moves with d by a fixed angle) until e meets f.

α = 0.3141592653589793 rad (slider from 0 to 1.5707963267948966, step 0.017453292519943295)
E = (9.240952380952384, 3.642857142857141)
D = (5.259047619047619, -5.360952380952381)
F = Rotate(E, α, D)
A = (7.66, -0.41999999999999904)
B = (9.56, -0.42)
C = (9.46, 2.8400000000000007)
poly1, c_1, a_1, b_1 = Polygon(A, B, C)
a = Line(D, E)
G = (-0.7000000000000001, 4.1)
c = Line(D, G)
A' = Mirror(A, a)
B' = Mirror(B, a)
C' = Mirror(C, a)
poly1', c', a', b' = Polygon(A', B', C')
b = Line(D, F)
A'' = Mirror(A', b)
B'' = Mirror(B', b)
C'' = Mirror(C', b)
poly1'', c'', a'', b'' = Polygon(A'', B'', C'')
A''' = Mirror(A'', c)
B''' = Mirror(B'', c)
C''' = Mirror(C'', c)
poly1''', c''', a''', b''' = Polygon(A''', B''', C''')
H = (-1.8828571428571401, -4.738095238095236)
d = Line(D, H)
A'_1 = Mirror(A, d)
B'_1 = Mirror(B, d)
C'_1 = Mirror(C, d)
poly1'_1, c'_1, a'_1, b'_1 = Polygon(A'_1, B'_1, C'_1)
β = Angle(E, D, F)