Exercise 19 Page 384

Before we can sketch the ray $\overrightarrow{AB}$ and the line $\overleftrightarrow{AC},$ we have to sketch the points $A,$ $B,$ and $C$ at arbitrary positions.

The ray $\overrightarrow{AB}$ starts at its endpoint $A,$ goes through $B,$ and continues on indefinitely. The line $\overleftrightarrow{AC}$ passes through both $A$ and $C,$ and continues on indefinitely in both directions.