DefinitionLines and planes in space are geometric objects in three dimensions. A line is specifiable by a direction vector and a point,and a plane is specifiable by a normal vector and a point. The positions and orientations of lines and planes are described by their equations. Describe an example: The line through the point (1,2,3) and with direction vector (4,5,6) is given by vector equation r(t)=(1,2,3)+t(4,5,6). The plane passing through (1,2,3) with normal vector (4,5,6) is given by 4(x−1)+5(y−2)+6(z−3)=0.
