40b. Position of a Ship at Sea from Two Known Points
Given two known, but inaccessible points A and B, to determine the location of two accessible unknown points P and P' from bearings on A and B.
Example: I am on a ship at sea and I take bearings from two familiar points on land. If I maintain a straight line course and take bearings twice I can determine my heading, and the two locations the bearings were taken.