It is really simple: .
Let u = <-1, 1, 2> and v = <2, -1, -1>. Find all unit vectors orthogonal to both u and v.
I know that one can use cross products to find a vector orthgonal to both u and v and scale it down to be a unit vector. But the question says to find all the unit vectors and I don't know how to go about doing that since there is an infinite number of them.