(i)[3]
Calculate the height of the centre of mass of the box above its base.
(ii)[4]
The box is then fitted with a thin uniform square lid of weight $3\,\text{N}$ and edge length $0.2\,\text{m}$. The lid is joined to the box by a hinge of length $0.2\,\text{m}$ and weight $2\,\text{N}$. The box lid is held partly open. Find the angle that the lid makes with the horizontal when the centre of mass of the box, including the lid and hinge, is $0.12\,\text{m}$ above the base of the box.