# False perpendicular bisector

Hello, I use the Poincare Disc Model in SAGE and I try to get the perpendicular bisector of a geodesic joining to points in the PD. It gives me a perpendicular geodesic, but it does not pass through the midpoint of my geodesic. I can not upload a screenshot of my situation so it is all I can say. Please help meee

Could you please provide the code that leads to the issue ?

Of course, it is the following

PD=HyperbolicPlane().PD() M=9 R=N(arccosh((cos(N(pi)/3.))/(sin(N(pi)/M)))) r=N(tanh(R/2)) B=PD.get_point(0+0

I) C=PD.get_point(rcos(N(pi)3/2)+rsin(N(pi)3/2)I) seg=PD.get_geodesic(B,C) seg2=seg.perpendicular_bisector() seg3=seg.perpendicular_bisector() seg.plot(color='blue')+(seg3).plot(color='red')The supposed perpendicular bisector of BC is a geodesic which seems to be perpendicular to it, but it does not divide BC by the midpoint, because it cross it outside the segment BC.