This question is not difficult. How could it be so wrong? The first problem to find the volume is the triangular pyramid. The volume formula is 1/3 times the bottom area times the height. The bottom surface is the upper surface of a cuboid, and the height is ready-made. The second problem is to find the angle. You have to connect AC 1 and use cosine theorem to solve this angle in the triangle. It is easy to solve.