Consider the vectors a=3it j - k, b=3i - j +k, c = i + 0.333333 j + 0.333333 k d = - i -3j+ k, g = i+3j +4k. Which pairs (if any) of these vectors are (a) Are perpendicular? (a,b) (Enter none or a pair or list of pairs, e.g., if a is perpendicular to b and c, enter (a, b), (a,c).) (b) Are parallel? (a,d) (Enter none or a pair or list of pairs, e.g., if a is parallel to b and c, enter (a, b), (a,c).) (c) Have an angles less than 7 /2 between them? (a,c),(b,d), (a,g), (a,b), (b,c), (b,g) (Enter none or a pair or list of pairs, e.g., if a is at an angle less than pi/2 from b and c, enter (a, b), (a,c).) (d) Have an angle of more than 7 /2 between them? (c,d),(a,d) Enter none or a pair or list of pairs, e.g., if a is at an angle greater than pi/2 from b and c, enter (a, b), (a,c).)