Find the ratio in which the yz-plane divides the line segment formed by joining the points (- 2, 4,7) and (3, - 5, 8).

The given points are A(-2,4,7 ) and B(3,- 5, 8). Let the point P (0, y, z) in yz-plane divides AB in the ratio k:1, thenr-coordinate of point P=mx2+nx1m+nk×3+1×(−2)k+1=0[∵x-coordinate of p is zero]⇒        3k−2    =0⇒k=23⇒        k:1    =2:3yz-plane divides the segment internally in the ratio 2:3.