please show the steps

6. Let O = (0, 0, 0), A = (0, 0, 1), B = (1, 0, 0), C = (1, 1, 0), D = (0, 1, 0). These are five of the eight vertices of a cube. Calculate: (a) (4 pts) The angle between AB and AC (b) (4 pts) The angle between AB and AD (c) (3 pts) The scalar projection of AD onto AB (d) (4 pts) The vector projection of AC onto AD