Question

A bridge builder wants to know the width of a river. He stands at point A along the river. He picks a point C directly across the river. He then walks downstream 90 feet from point A to point B. From point B, he sites C and determines the angle between the bank and point C (θ), to be 43º. What is the width of the river?

Answer 1

width = 90 tan43 degrees = about 84 feet