A line continues infinitely in both directions. This is indicated by arrows on both ends, so $\displaystyle{\stackrel{{\leftrightarrow}}{{{E}{D}}}},{\stackrel{{\leftrightarrow}}{{{B}{E}}}}\usepackage{cmbright}\Huge\$ are the only lines. A ray continues infinitely in one direction. This is indicated by an arrow on the end. For each of the six arrows in the picture there is a ray: $\displaystyle{\stackrel{{\to}}{{{E}{A}}}}\usepackage{cmbright}\Huge\$ , $\displaystyle{\stackrel{{\to}}{{{E}{B}}}}\usepackage{cmbright}\Huge\$ (points up), $\displaystyle{\stackrel{{\to}}{{{B}{E}}}}\usepackage{cmbright}\Huge\$ (points down), $\displaystyle{\stackrel{{\to}}{{{E}{C}}}}\usepackage{cmbright}\Huge\$ , $\displaystyle{\stackrel{{\to}}{{{E}{D}}}}\usepackage{cmbright}\Huge\$ (points to the right), and $\displaystyle{\stackrel{{\to}}{{{D}{E}}}}\usepackage{cmbright}\Huge\$ (points to the left).