Question

I know the answer is 2 degree but I don't know how to do it.

Answer 1

nvm

Answer 2

If you were standing on the runway looking at the airplane, the angle of elevation
to the airplane would equal the angle of depression the pilot would experience if
the pilot could see you.

The angle Looking at the airplane while on the runway is the arc tangent of
the height of the airplane, 10000 ft, divided by the distance from the airplane's nadir,
that point directly below the airplane, to the point where you are standing on the runway.

Mathematica calculated 2.16926 degrees or 2 degrees rounded to the nearest degree.