How are statically indeterminate structures analyzed?

When equilibrium equations are insufficient (reactions > equations), compatibility equations based on deformations are needed. Methods include: Superposition (solving determinate cases and combining), Flexibility/Force method (redundant forces as unknowns), Stiffness method (displacements as unknowns, basis of FEA), and Three-moment equation for continuous beams. These structures are more rigid and distribute loads better.