Here is the problem:
An airplane is flying 6 miles above the Earth's surface. Find point H. (H is a point on the earth's surface). The given radius of the earth is 4000 miles.
Was that all of the question? It seems like it hasn't given you enough information for you to do anything.
Why did the vector cross the road?
It wanted to be normal.
What? Mathsyperson if you take a pencil and make points with until you cover the earth you will only have a little under 328 million marks to choose from. You can't figure H from that?