BONUS: The following problem is modeled after a surveying question developed by a Chinese mathematician during the Tang dynasty in the seventh century C.E.

A building sits on the edge of a river. A man views the building from the opposite side of the river. He measures the angle of elevation with a handheld tool and finds the angle measure to be 45°. He moves 50 feet away from the river and remeasures the angle of elevation to be 30°.

What is the height of the building?