Consider the vectors
a=5i+j-k, b= -i+5j +0K, c=i+j+6k
d=-5i-j+ k, g=-i-5j+k
Which pairs (if any) of these vectors are
(a) Are perpendicular?
(Enter none or a pair or list of pairs, e.g., if á is perpendicular to b and e, enter (a,b),(a,c).)
(b) Are parallel?
(Enter none or a pair or list of pairs, e.g., if ä is parallel to band è, enter (a,b),(a,c).)
(c) Have an angles less than pi/2 between them?
(Enter none or a pair or list of pairs, e.g., if ä is at an angle less than pi/2 from b and č, enter (a,b),(a,c).)
(d) Have an angle of more than π/2 between them?
(Enter none or a pair or list of pairs, e.g., if ä is at an angle greater than pi/2 from b and ĉ, enter (a,b),(a,c).)