α

Du kannst α mit dem Schieberegler verändern 
und Z durch anklicken verändern.

ABC

Z

A'B'C'

α

Dreieck drehen

Z = (1, 1)
B = (3.8344438526653093, 2.1880226353314494)
α = 0.6283185307179586 rad (slider from 0 to 6.283185307179586, step 0.017453292519943295)
a = Segment(Z, B)
B' = Rotate(B, α, Z)
β = Angle(B, Z, B')
b = Segment(Z, B')
A = (5.6305661565254495, -3.0424434143711547)
C = (7.347738029446681, -1.0292074254290204)
D = (7.485901283589769, -3.8319477237602273)
Vieleck1, d, a_1, c = Polygon(A, C, D)
E = (2.551499349908067, -3.0029681989017014)
A' = Rotate(A, α, E)
C' = Rotate(C, α, E)
D' = Rotate(D, α, E)
Vieleck1', d', a', c' = Polygon(A', C', D')
e = Segment(A, E)
f = Segment(A', E)
γ = Angle(A, E, A')
g = true