Example With planes: P1:2x−2y+5z+10=0 P2:2x+y−4z+7=0 We get: n1=(2,−2,5) n2=(2,1,−4) The line of intersection is the solution for system of equation ⟹3y−9z−3=0 ⟹y=3z+1 ⟹2z+3z+1−4z+7=0 ⟹x=2z−4 ⟹ we get the line relations by setting z as2t: x=t−4 y=6t+1 z=2t, t∈R ⟹ we get the line: (−4,1,0)+t(1,6,2)