Prove that the line through `A(0,1,1)` and `B(4,5,1)` intersects the line through `C(3,9,4)` and `D(4,4,4)` .

Prove that the lines through A(0,-1,-1) and B(4,5,1) intersecrs the line through C(3,9,2) and D(-4,4,4). Also,find their point of intersection.

Show that the line through points (4,7,8) and 2,3,4 ) is parallel to the line through the points (-1,-2,1) and (1,2,5) .

Find the value of p for which the line through the points A(4,1,2) and B(5,p,0) is perpendicular to the line through the points C(2,1,1) and D(3,3,-1) .

Find the equation of the line passing through (2,1,-2) and (5,3,4) and of the plane passing through (2,0,3) , (1,1,5) and (3,2,4) . Also find their point of intersection.

Show that the line through the points (1,-1,2),(3,4,-2) is perpendicular to the line through the points (0,3,2) and (3,5,6)

Show that the line through the points (1,-1,2) and (3,4-2) is perpendicular to the line through the points (0,3,2) and (3,5,6).

Show that the line through the points (-2, 6) and (4, 8) is perpendicular to the line through the points (3,-3) and (5,-9).

Show that the line through the point (4, 7, 8) and (2, 3, 4) is parallel to the line through the points (-1, -2, 1) and (1, 2, 5).

Find the coordinates of the point where the line through (3,-4,-5) and (2,-3,1) crosses the plane passing through the points (2,2,1),(3,0,1) and (4,-1,0).

Show that the line thorugh the points (4,7,8) and (2,3,4) is parallel to the line through the points (-1,-2,1) and (1,2,5) .