The skipper of a boat knows that the water is too shallow to bring his boat inside a "danger semicircle" that goes from lighthouse to lighthouse. How can the angle between his sightings of the two lighthouses help him decide when he is entering the danger zone?

Question

How can I figure this out. There is a picture, but there aren't any numbers or angles on it. It seems to be a theory problem and I reread my book's section on this and still do not get it.

Please help me!!!

Answer 1

the included angle from boat to one lighthouse to the other call angle A.

No if the boat is on the perimeter of the semicircle, that angle A is 90 deg.
If outside the circle, the angle will be less.