Question 1:
[1, 1, 1] & [3, -2, 1]

[1, 1, 1].[3, -2, 1]
= 1(3), 1(-2), 1(1)
= [3, -2, 1]
= 3-2+1 = 2
= 2

sqrt(1+1+1) = sqrt(3)
sqrt(3^2+(-2)^2+1) = sqrt(14)

arccos(2/(sqrt(3)sqrt(14)))
theta = 67.8 = Acute


Question 2:

<4, 3> & <2, -4>
u.v = 4(2) + 3(-4) = -4
arccos(-4/((sqrt(25)sqrt(20)))
theta = 100.3 = Obtuse



Question 3:

[0 1 -1]= v
w = [1, -1, 0]

i  j  k
0  1  -1
1  -1  0

((0)-(-1*-1)) - ((0)-(-1*1)) + (0-(1*1)) = [-1, -1, -1]