α = 0 rad (slider from 0 to 6.283185307179586, step 0.0017453292519943296)
B = (5.4, 0.3)
r = 6
C: B + (r, 0.0)
C' = Rotate(C, α + 225.0°, B)
D = Rotate(C, α + 315.0°, B)