Question

|u| = 4, |v| = 4, and the angle between u and v (when placed tail to tail) is 90 degrees. Find |u| - |v|

a) -1
b) 5
c) 25
d) 12

Answer 1

We know
u dot v = |u| |v| cos θ , where θ = 90°
u dot v = (4)(4)cos90 = 0
of course we already know that the dot product between perpendicular
vectors is 0

Your question is:
find |u| - |v| , but since you said: |u| = 4, |v| = 4
= 4-4
= 0

am I missing something here?

Answer 2

oh sorry i meant that |u| = 3, |v| = 4