Extracted text: Problem 3. Classify each of the structures shown as externally unstable, statically determinate, or statically indeterminate. If the structure is statically indeterminate externally, then determine the degree of external indeterminacy. Hinge Hinge 3.1 (a) Hinge (b) (c) (d) Hinge Hinge Hinge Hinge Hinge (a) 3.2 Hinge Hinge (b) (c) (d)