Inside an old ranger station, Emek and Tara discovered faded blueprints for a historic mountain bridge. Several angle measurements at the intersections of the structural beams had disappeared over time. One drawing showed a 74° angle where two beams crossed, while another adjacent angle was missing. Using the facts that vertical angles are equal and adjacent angles on a straight line are supplementary, they calculated the remaining angles as 74° and 106°. Repeating this reasoning throughout the blueprint, they reconstructed the original engineering layout and revealed how the bridge had been designed to support heavy loads.