Odgovor:
# j = 8 #
Pojasnilo:
#costheta = ((a + jb).c) / (abs (a + jb) abs (c)) #
Vendar pa # theta = 90 #, Torej # cos90 = 0 #
# (a + jb).c = 0 #
# a + jb = ((2), (2), (2)) + j ((- 1), (2), (1)) = ((2-j), (2 + 2j), (2) + j)) #
#c = ((3), (1), (0)) #
# (a + jb).c = 3 (2-j) + 2 + 2j = 6-3j + 2 + 2j = 8-j = 0 #
# j = 8 #