Distance in the Horizon
Because of earth's curvature, a person can see a limited distance to the horizon. The higher the location of the person, the farther that person can see. The distance D in miles to the horizon can be estimated by D(h)=1.22 sqrt{h}, where h is the height of the person above ground in feet.

a. How high does a person need to be to see 20 miles?

Question

Distance in the Horizon
Because of earth's curvature, a person can see a limited distance to the horizon. The higher the location of the person, the farther that person can see.  The distance D in miles to the horizon can be estimated by D(h)=1.22 sqrt{h}, where h is the height of the person above ground in feet.

a.  How high does a person need to be to see 20 miles?

radar · Answer

It looks like the equation takes care of the conversion of miles and feet, so we can just do it this way:$$20=1.22\sqrt{h}$$$$\sqrt{h}=20/1.22=16.39$$  Squaring
h=268.745 feet

radar · Answer

I have seen this equation before, it was used for determining antenna height for  "line of sight" communications paths.

anonymous · Answer

ty so much radar, i am hopeless with this math i swear

radar · Answer

Keep up the effort and with practice it will be better.

anonymous · Answer

I hope so, final exams are tuesday, i wish i had a good printout step by step on how to do problems