1.97: 3D angles in a pyramid

Figure 2 shows a solid which is formed by joining a cuboid to a right pyramid . The height of the cuboid and the height of the pyramid are both cm and cm and cm. The total volume of the solid is .
(a) Show that . (2)
(b) Find, in cm to 3 significant figures, the length of . (3)
Find, to the nearest ,
(c) the angle between and the plane , (3)
(d) the acute angle between the plane and the plane . (4)
