Eric Nicholas K's answer to Jae's Junior College 1 H2 Maths Singapore question.

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
I forgot much of my vectors already but I have tried my best here; the geometrical interpretation is something to do with the projection length of one vector onto another.

Recall that i.i = j.j = k.k = 1 and i.j = i.k = j.k = j.i = k.i = j.k = 0.