Problem with Series

1. Sep 19, 2009

Jery

1. The problem statement, all variables and given/known data
If you are on top of a tower height, h, above the surface of the earth, show the distance you can see along the surface is s=$$\sqrt{2Rh}$$ where R=radius of earth.
hint--show h/R= sec$$\Theta$$ - 1, find two terms of series sec$$\Theta$$= 1/cos$$\Theta$$ and use s=R$$\Theta$$.

2. Relevant equations

The equations for the series of cos$$\Theta$$. Also I am guessing some basic trig formulas.

3. The attempt at a solution
The real problem is I just can't get this started for some reason. If someone could give me a hint that lets me see how to get started and then I can get the solution myself then that would be great. Thanks.