A = (-0.74, 3.8000000000000003)
B = (4.48, -2.94)
C = (-3, -2.94)
poly1, c, a, b = Polygon(A, B, C)
D = Midpoint(c)
α = 0 rad (slider from 0 to 3.141592653589793, step 0.017453292519943295)
A' = Rotate(A, -α, D)
B' = Rotate(B, -α, D)
C' = Rotate(C, -α, D)
poly1', c', a', b' = Polygon(A', B', C')