Given u = (3, 1,-2), v = (2,0,−1), w = (-1, 1, 2) find the cosine of the angle between (vxw) and (u × v). (1) cross (X) the correct answer:
a. 2/21
b. -1/21
c. -1/√21
d. √2/√21
e. -1/√7
f. 2/√7