I'm a junior in an honors trigonometry class, and am also studying some more advanced physics on my own. So i've decided to try to solve the problem accounting for the speed of light. here is the problem. An airplane is sighted at the same time by two ground observers who are 4 miles apart and in line with the airplane. They report the angles of elevation as 15 and 20 degrees. How high is the airplane? I've rendered this problem unsolvable, and here is my reasons. Because the plane is sighted by both parties simultaneously, that must mean the line of sight distance in both cases must be equal because the speen of light is finite and constant. Therefore, you have 2 systems with two variables each, both have a varying height of the plane and distance to the point under the plane. The only info you have is one angle in each triangle, and that these triangle's hypotonuses are equal. Does this make sense to anybody else?