A mapmaker has successfully mapped Carlisle Street and River Avenue, as shown in the diagram. The last step is to map Beacon Street correctly. To save time, the mapmaker intends to measure just one more angle or side of the triangle. Which angle(s) or side(s) could the mapmaker measure to be sure that only one triangle is possible? For each angle or side that you name, justify your answer. Suppose that instead of measuring the length of Carlisle Street, the mapmaker measured ∠A and ∠C along with ∠B. Would the measures of the three angles alone assure a unique triangle? Explain.