The position vectors for points P and Q are 4 I + 3 j + 6 j + 6 k respectively. Express vector PQ in terms of unit vectors I, j and k. Hence find the length of PQ, in simplified surd form.

Answer 1

It doe not look too clear what P and Q are, I am assuming the following.

P=(4,3,0)
Q=(0,6,6)

PQ = Q-P = <4,-3,-6> by subtraction
= 4i-3j-6k in unit vectors.

Length of vector
<x,y,z> = sqrt(x^2+y^2+z^2)