- find the ratio in which the line segment joining the points (2,-1,3)and (-1,2,1) is divided by the plane x+y+z=5
let the given points are A(2, -1, 3) and B(-1, 2, 1).
let the line segment AB is divided by the plane x+y+z = 5.......(1) in the ratio k : 1.
therefore by the section formula: coordinates of the intersecting point are
this point must lie on the given plane (1):
thus it divides externally in the ratio 1 : 3.
hope this helps you.