To Find the Distance Across a River a Surveyor Chooses $A$

Essay

To find the distance across a river a surveyor chooses points $A$ and $B$ , $50$ m apart and a reference point $C$ on the opposite side of theriver. Approximate the distance, $b$ , between $A$ and $C$ given that $\angle \mathrm { A } =54 ^ { \circ }$ and $\angle B = 77 ^ { \circ }$ .