HP2 = split a regular heptagon in 2 equal area pieces with minimum perimeter
     origin of coordinates:  in the middle of the pentagon
     if there are symmetries in the solution the data are given only for the significant part
     radius of circumscribed circle = 1

border
     (           0,	-1)
     ( 0.781831482,	-0.623489802)
     ( 0.974927912,	0.222520934)
     ( 0.433883739,	0.900968868)
     (-0.433883739,	0.900968868)
     (-0.974927912,	0.222520934)
     (-0.781831482,	-0.623489802)
     (           0,	-1)

vertex 1    (0.909888472,	-0.062435472)
     arc 11 (          0,	-4.04891734 ) 4.089001676  [centercoordinates and radius]

yields the following cutlength
     CL* = 1.835139661       in units of sidelenght: CL=CL*/(2*0.433883739)=2.114782712