Determine whether the given vectors are orthogonal, parallel, or neither.
a) a = (9, 3), b = (-2, 6)
o orthogonal
o parallel
o neither
b) a = (4, 5, -2), b = (3, -1, 5)
o orthogonal
o parallel
o neither
c) a = -4i + 12j + 8k, b = 3i - 9j - 6k
o orthogonal
o parallel
o neither
d) a = 2i - j + 2k, b = 5i + 6j - 2k
o orthogonal
o parallel
o neither
