DefinitionLines and planes in space are three-dimensional geometric objects. Vector DIR is the direction of a line, P is the point on the line OR a point to determine a plane, and the VPLANE is the normal of the plane. Equations give us the location of the lines and planes as well as the direction. Such as: The line through (1,2,3) having direction vector (4,5,6) is expressed as r(t)=(1,2,3)+t(4,5,6) vector equation 4 The equation to the plane passing through (1,2,3) with its normal vector: (4,5,6) is 4(x−1)+5(y−2)+6(z−3)=0