Show that the line joining the origin to the point (2,1,1) is perpendicular to the line determined by the points `(3,5,-1) and (4,3,-1)`.

Show that the line joining the origin to the point quad (2,1,1) is perpendicular to the line determined by the points (4,3,-1)

Show that the line joining the point A(1,-1,2) and B(3, 4, -2) is perpendicular to the line joining the points C(0,3,2) and D(3,5,6).

Show that the line joining the points (4,-3) and (0,7) is perpendicular to the line joining the points (5,2) and (0,0) .

Show that the line through the points (-2,6) and (1,7) is perpendicular to the line through the points (3,-3) and (5,-9).

Show that the line joining the points (2,-6) and (-4,-8) is perpendicular to the line joining the points (4,-2) and (6,-8) .

Determine the value of k so that the line joining points A(k,1,-1) and B(2,0,2k) is perpendicular to the line joining the points C(4,2k,1) and D(2,3,2) .

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

Line joining the points (3,-4) and (-2,6) is perpendicular to the line joining the points (-3,6) and (9,-18).

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)