19. The cross product has an interesting geometric interpretation. Let u, u be vectors in R and Wux. Then ||w|| = A, where A is the area of the parallelogram spanned by u, v. In other words, if is the angle between u and |||||||||||| sin(0) = Prove this for u = (0,3,3), = (2,1,2). 20. Let u, v E R. Show that || v|| + |uv| = ||||||||| Hint: there's an easy way and a hard way.