The vectors b and c are in the direction of north-east and north-west respectively and |b|=|c|=4. The magnitude and direction of the vector d = c - b, are
4√2, towards west
Clearly, b⊥c,∴b.c=0
Now, d = c - d ⇒|d|2=|c−b|2
=|c|2+|b|2−2b.c=16+16−0
⇒|d|=√32=4√2 and direction of d is west.