1. Determine whether the vectors [2,-1] and [-2,-5] are orthogonal.
I remember learning this stuff last year and I think it has something to do with the dot product of vectors maybe? Help would be greatly appreciated.
2. Find the angle between vector u = [-2, 5] and vector v= [-1, 3].
Once again, I completely forget how to do this. Cross product?
I am still re-learning my Algebra and have not started on pre-calc yet, but from what I remember about vectors, this notation [2,-1] is the distance of the vector from the origin in the x and y directions, correct?
If this is the case, could you not also solve this problem by calculating then comparing the slope of both vectors as lines?
ie,
since , vectors are not orthogonal.
Is this approach correct?