[" The midpoint of "A(x_(1),y_(1),z_(1))" and "B(x_(2),y_(2),z_(2))],[" is "]

The distance between the points A(x_(1),y_(1),z_(1)) and B(x_(2),y_(2),z_(2)) is AB=

Find the distance between the points P(x_(1),y_(1),z_(1)) and Q(x_(2),y_(2),z_(2))

XY - plane divides the line joining A(x_(1),y_(1),z_(1)) and B(x_(2),y_(2),z_(2)) in the ratio

Prove that the line segment joining (x_(1),y_(1),z_(1)) and (x_(2),y_(2),z_(2)) is divided by XY,YZ,ZX-plalnes respectively in the ratio -z_(1) : z_(2),-x_(1) :x_(2),-y_(1) : y_(2) .

Assertion (A): A(x_(1),y_(1),z_(1)), B(x_(2),y_(2),z_(2)) . The projection of AB on the line with D.C's (l,m,n) is l(x_(2)-x_(1)) +m(y_(2)-y_(1))+n(z_(2)-z_(1)) Reason (R ) : The projection of the join of A (x_(1),y_(1),z_(1)), B(x_(2),y_(2),z_(2)) on yz plane is sqrt((y_(2)-y_(1))^(2)+(z_(2)-z_(1))^(2))

The midpoint of the line segment joining A(x_(1),y_(1),z_(1)),B(x_(2),y_(2),z_(2)) is

The coordinates of any point on the line-segment joining the points ( x _(1) ,y_(1) , z_(1)) and (x_(2), y_(2),z_(2)) are ((x_(1)+kx_(2))/(k + 1),(y _(1) + ky_(2))/(k + 1),(z_(1)+kz_(2))/(k + 1)) , then the value of k will be _

The line segment joining A(x_(1),y_(1),z_(1)),B(x_(2),y_(2),z_(2)) is divided by XY - plane in the ratio