Question

Given that P (3, 2, -4), Q(5, 4, -6) and R (9, 8, -10) are collinear. Find the

ratio in which Q divides PR.

Answer 1

P (3, 2, -4), Q(5, 4, -6) and R (9, 8, -10)

PQ $=\sqrt{(5-3{)}^2+(4-2{)}^2+(-6+4{)}^2}=\sqrt{4+4+4}=2\sqrt{3}$

QR =$\sqrt{(9-5{)}^2+(8-4{)}^2+(-10+6{)}^2}=\sqrt{16+16+16}=4\sqrt{3}$

Thus, PQ : QR = 1 : 2