Question

The unit vector in the direction from point A having
coordinate (1, –1, 2) to point B having coordinate
(–1, 1, 1) is

Answer 1

Given the points   (1, –1, 2) & (–1, 1, 1)

You make a vector in the direction from one point to another by subtracting each starting coordinate from its respective ending coordinate:

V = (1+1)i +(-1-1)j+(2-1)k

v=2i-2j+k

| v|= √(2² + (-2)² + 1²) = √(4 + 4 + 1 )= √9 = 3

The unit vector in the direction from point A having

coordinate (1, –1, 2) to point B having coordinate

(–1, 1, 1) is = V/ |V| = (2i-2j+k)/3