Question

describe all unit vectors orthogonal to v = i + j + k

Answer 1

is it when u cross v=0 tells that u is orthogonal to v? I can't remember

Answer 2

Question is rarely asked like this. Usually you are given 2 vectors. I imagine if you find the dell, that would be orthogonal.

Answer 3

ok so its dot product that tells us if two vectors are othogonal
if u dot v=0 then u and v are othogonal
v=(1,1,1) and u=(u1,u2,u3)
u dot v=u1+u2+u3=0
you choose values for u1,u2,u3 as long as the sum =0