posted by Joe .
Because of the Earth’s curvature, a person can see a limited distance to the horizon. The higher the location of the person, the farther the person can see. The distance D in miles to the horizon can be estimated by D(h)=1.22√h, where h is the height of the person above the ground in feet. How high does a person need to be to see 28 miles? A person need to be about ? many feet high.