G.516 parallel planes — Heath

XI.def.8

Parallel planes are those which do not meet.

Required for

G.517, G.518, G.519, G.520, G.530, G.531, G.541, G.542, G.543, G.544, G.546, G.547, G.550, G.554, G.555, G.556, G.557, G.558, G.559, G.560, G.563, G.565, G.570, G.571, G.572, G.573, G.577, G.578