This document discusses calculating deflections in statically indeterminate trusses. It provides an example of calculating the deflection at point E in a pin-jointed truss subjected to a load P by drawing the free body diagram, analyzing bar forces, determining individual bar deflections, constructing a deflection diagram, and calculating the total horizontal and vertical displacement. It also discusses how statically indeterminate trusses can be analyzed by setting up simultaneous equations involving unknown reactions and forces, using compatibility conditions from known displacements, and employing techniques like superposition and symmetry.