- Statically determinant: # unknown forces = # static eqns. - To identify, look for redundant supports - Element force-deformation behavior: $e_{n}=\frac{F_{n}L_{n}}{E_{n}A_{n}}$ - $e$ -> elongation; $u$ -> displacement $(x)$; $v$ -> displacement $(y)$ --- $ e_{1}=u_{c}\cos\theta_{1}+v_{c}\sin\theta_{2}\quad e_{2}=u_{c}\cos\theta_{2}+v_{c}\sin\theta_{2} $ where $\theta_{n}$ is measured CCW from the positive axis 1. Equilibrium: FBDs & equilibrium eqns. 2. Load/deformation: find $e_{n}$ w/ conventions defined in book 3. Compatibility: enforce fixed displacement -> elongation eqns. 4. Solve system of eqns.