Question 1148544
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In your post the point "C" is nor defined,


therefore, the condition is uncompleted and the question CAN NOT be answered.



Also, it is not stated on how these points relate to the Earth


and what does it mean that the points A and B are "d" miles apart.



This distance "apart" can be measured by DIFFERENT WAYS in this context, giving different answers to the problem.



My point is : until the problem's formulation and its meaning are not clearly established,

any solutions / "solutions"  are pure speculations.