Heath ID: I.def.23

G.37

Parallel straight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction.

Required for

G.38, G.39, G.44, G.45, G.46, G.49, G.50, G.51, G.52, G.53, G.54, G.55, G.57, G.58, G.59, G.60, G.61