ABCDEF is a regular hexagon where centre O is the origin, if the position vector of A is `hati-hatj+2hatk,` then `bar(BC)` is equal to

ABCDEF is a regular hexagon where centre O is the origin,if the position vector of A is hat i-hat j+2hat k, then bar(BC) is equal to

A, B, C, D, E, F in that order, are the vertices of a regular hexagon with centre orgin. If the position vectors of the vertices A and B are respectively, 4hati+3hatj-hatk and -3hati+hatj+hatk , then DE is equal to

If ABCDEF is a regular hexagon of side a, then bar(AB).bar(AF)=