vector multiplication, Prob46

Hi

Please have a look on the attachment and kindly help me with the query, Q1, there. This is the book I'm using; for the current problem go to page #35.

Q2: I understand that coplanar vectors are those which exist on the same same plane. The unit vectors i, j, and k are non-coplanar vectors and are perpendicular to each other (in other words the planes in which they exists are at 90 degrees to each other). Is it necessary for non-coplanar vectors to be be perpendicular to each other.


Many thanks for your time.

Regards
PG

PG,

Q1: By simple vector algebra. (b-a)x(c-a) = b x (c-a)-a x (c-a) = b x c -b x a -a x c+a x a = b x c + a x b + c x a +0

Ratch