Plane-section geodesics of the unit one-sheet hyperboloid
= Plane-section geodesics of the unit one-sheet hyperboloid
On $x^2+y^2=z^2+1$, an axial plane such as $y=0$ cuts out two disjoint meridian geodesics. The tangent plane $x=1$ cuts out the two straight ruling lines $y=\pm z$, which are geodesics meeting orthogonally at $(1,0,0)$.