Ideal endpoint
= Ideal endpoint
An ideal endpoint of a <hyperbolic line> is one of its two limiting points on the boundary at infinity. In the <Poincare disc model> these lie on the unit <circle>; in the <upper half-plane model> they lie on $\mathbb R\cup\{\infty\}$. These are boundary points, not points of the <hyperbolic plane>. Any two distinct <ideal endpoints> determine a unique <hyperbolic line>.