Question

If A=4i^ +3j^ -2k^ and B=8i^ +6j^ -4k^, the angle between A and B is?

Answer 1

Use
A.B = |A| |B| cosQ

Here A. B is dot product
|A| |B| are magnitudes of A and B which is calculated by,
root over Asquare +Bsquare +Csquare
Q is the angle between two vectors.

Hope you get your answer.

Answer 2

Answer:

angle=0°

Explanation:

cos θ = {(A➙ ∙ B➙) / (|A| |B|)}

A➙ ∙ B➙ = (4i˄ + 3j˄ – 2k˄) ∙ (8i˄ + 6j˄ – 4k˄)

                  = (4) (8) + (3) (6) + (– 2) (–4)  

                   = 32 + 18 + 8

                   = 58

|A| = √(42 + 32 + 22)

         = √29

|B| = √(82 + 62 (– 4)2)

      = √116

cos θ = [{58} / {√(29) ∙ √(116)}]

= 1

hence θ = 0°