A person standing h feet above sea level can seecd miles to the horizon. The distance r is the radius of the earth = 3963 miles. d is the tangent to the circle forming a right angle to the radius. h + r is the tangent. Solve using Pythagorean theorem and secant-tangent theorem. I don't know if this is important but the question also says mount everest summit reaches 29,035 feet above sea level.

2 answers

If you draw a triangle where the hypotenuse is r+h (the elevated observation point), and the distance to the horizon is d, then

r^2+d^2 = (r+h)^2
Thanks Steve. I got it. Forgot to convert feet to miles when calculating.