Answer:
216.2 mi
Explanation:
The Pythagorean theorem can be used to find the unknown leg of the right triangle in this geometry. It tells you the sum of the squares of the legs of the triangle is equal to the square of the hypotenuse.
x^2 +3959^2 = (3959 +5.9)^2
x^2 = 15,720,432.01 -15,673,681 = 46,751.01
x = √46,751.01 ≈ 216.2
From point P to the horizon is about 216.2 miles.