a) Ok, so we have two vectors

a = <3, 2, sqrt(3)>

b = <3, 1, sqrt(6)>

We should begin by determining some kind of formula for this:

||a||*||b||cos(x) = a*b

So first we find the magnitude of each of these vectors, which is:

||a|| = (9 + 4 + 3)^.5 = 4

||b|| = (9 + 1 + 6)^.5 = 4

We should also find the dot product of these two vectors:

3*3 + 2*1 + sqrt(9) = 9 + 2 + 3 = 14

So now we plug it all in

4*4 cos(x) = 14

cos(x) = 14/16

cos(x) = .875

arccos(.875) = 28.95 degrees or .505 radians

As for b I cannot help you... Unfortunately.