The angle between A= hat(i) + 2hat(j) - hat(k) and bar(B)= -hat(i) + hat(j)-2 hat(k) is

The angle between A= hat(i) + 2hat(j) - hat(k) and bar(B)= -hat(i) + h

1.	The angle between A= hat(i) + 2hat(j) - hat(k) and bar(B)= -hat(i) + hat(j)-2 hat(k) is
Answer» `30^(@)` `45^(@)` `60^(@)` `90^(@)` ANSWER :C