It is given the person standing at the top of a skyscraper is approximately 0.39 mi high. We need to find how far out on the earth's horizon could this person be seen.The earth radius is given as 3959 mi .
The Earth can be considered as a sphere.The distance from the center of earth to the person on skyscraper =3959+0.39=3959.39 miles
From the top of the building, we extend a tangent which will intersect with the extended radius of the earth. We then have a 45-45-90o triangle We can use
Pythagorean theorem
to find x that is how far the person can see.
x² = 3959.34² - 3959²
x = √(3959.34² - 3959²) miles
x=55.57
Or x= 56 miles the person can be seen.
