

1.2 Three Dimensional Space


There are points, lines and planes.
 Any plane is a 2 dimensional space as already discussed.
 Three points not on a line determine a plane containing all three;
 A point and a disjoint line determines a unique plane containing both;
 A point and a direction or line determines a unique plane normal to
the line through the point.
 2 lines either lie in a single plane or are skew (not both).
Points can be considered as abstract objects. To conveniently represent their
properties we usually introduce some additional structure. In particular we
describe points and lines and planes by using vectors, and obtain numerical
representations of the vectors by introducing an origin and a set of
basis vectors.