Given a rectangular prism of edge length D and height L subjected to a vertical load F (force) applied to the prism ends and a horizontal pressure p applied to the sides of the prism, find

(a) the forces N and T acting normal and tangential to a surface inclined at an angle θ to the vertical, measured in a plane parallel to a side of the prism and
(b) stresses, that is, the forces per unit area, σ and τ on the inclined surface in terms of the applied stress σo (F/A), and pressure p where A is the area acted on by F. Illustrate with sketches.