In conducting a land survey, the following problem arose. There were two points A and B along a road and points C and D off the road along the respective perpendiculars to the road at A and B. There were buildings on the property that prevented direct measurement of the distances along BD and AC. Measurements, however, could be made for AD, BC, and AB as follows:
A light pole is to be installed at point E, the intersection of CB and AD. How far will the pole be from the road? That is, what is the distance EF? Again, an existing building blocks direct measurement.
Compare this problem to How Wide is the Alley?