If u and v are vectors such that..

|u|=2 , |v| = 3 and the angle between u and v is pi/3
a)Find the exact value for |u - 2v|

b) let u = <4,-8,1> , v = <2,1,-2> and w = <3,-4,12> determine if the vectors u,v and w are coplanar. Justify your answer

c) Let u,v and w be vectors such that u . (v x w) = 3 Find
(i) u.(w x v) (ii) (u x w).v (iii) v.(w x w)

need help with this questions! would be much appreciated if someone could give us a hand!