9. [Perpendicular Vectors] Find two unit vectors perpendicular to (2,-2,-3) and (0,2,1).
10. [P] [Parallelograms and Parallelepipeds]
(a) Calculate the area of the parallelogram in $R^2$ generated by (1,2) and (-2,3).
(b) Calculate the area of the parallelogram in $R^3$ generated by (3, -1, 1) and (1,5,0).
(c) Calculate the volume of the parallelepiped in $R^3$ generated by (3,-1,1), (1,5,0), and (-2,2,3).