T4 = split regular triangle in 4 equal area pieces with minimum perimeter (modified Hall)
     origin of coordinates:  in the middle of the base
     if there are symmetries in the solution the data are given only for the significant part

border
     (0, sqrt(3)/2)
     (+0.5, 0)
     (-0.5, 0)

vertex 1    ( 0.09738741,  0.396898262)
     arc 11 (          0,  0.014150287) 0.398709723  [centercoordinates and radius]
     arc 12 ( 0.491830328, 0.014150287) 0.549619166  [centercoordinates and radius]
     arc 13 (-1.299440454,           0) 1.452121314  [centercoordinates and radius]


yields the following cutlength
     CL = 1.305113032