Hyperbolic Line Construction B41C19
1. **Problem statement:** We have a hyperbolic line $l$, a point $A$ on $l$, and a point $B$ outside $l$. We need to construct:
(a) One hyperbolic line $h_1$ parallel to $l$ passing through $B$, and one hyperbolic line $h_2$ intersecting $l$ passing through $B$.
(b) The hyperbolic line passing through both $A$ and $B$.
2. **Key concepts:**
- In hyperbolic geometry, through a point not on a given line, there are infinitely many lines that do not intersect the given line (parallel lines).
- A hyperbolic line is represented by an arc of a circle orthogonal to the boundary circle $H$.
- To construct lines through $B$, we find arcs orthogonal to $H$ passing through $B$.
3. **Step (a) construction:**
- To construct $h_1$ (parallel to $l$ through $B$):
- Identify the circle defining $l$ (orthogonal to $H$).
- Construct a circle orthogonal to $H$ passing through $B$ that does not intersect $l$ inside $H$.
- This circle's arc inside $H$ is $h_1$.
- To construct $h_2$ (intersecting $l$ through $B$):
- Construct a circle orthogonal to $H$ passing through $B$ that intersects the circle defining $l$ inside $H$.
- The arc inside $H$ is $h_2$.
4. **Step (b) construction:**
- The hyperbolic line through $A$ and $B$ is the unique circle orthogonal to $H$ passing through both points.
- Find the circle orthogonal to $H$ that passes through $A$ and $B$.
- The arc inside $H$ is the hyperbolic line through $A$ and $B$.
5. **Summary:**
- $h_1$: circle orthogonal to $H$ through $B$ parallel to $l$.
- $h_2$: circle orthogonal to $H$ through $B$ intersecting $l$.
- Line through $A$ and $B$: unique circle orthogonal to $H$ through both points.
This completes the constructions as per hyperbolic geometry rules.