How far can you see through the window of an airplane at an altitude of 12,000 meters?

Question

The formula D = 3.5 √h tells how many kilometers (D) you can see from a height (h) in meters above the earth, How far can you see through the window of an airplane at an altitude of 12,000 meters?

Answer 1

I just got off an A380 from Seoul to L.A.  I could see from the plane down to the Earth's cloud cover.

 

In cloudless conditions, make a sketch of the situation, using known dimensions, and use Trigonometry to find distance to Earth, along a line tangent to Earth and using radius of Earth = 3569 miles. (Conversion of units will be required since h is in meters.)