## How to Convince Your Flat-Earth Friends the Earth Is Round

Illustration: Rhett AllainYou can see that we have a right triangle with the hypotenuse equal to the distance from the observer's eyes to the center of the Earth (R + h), with the other two sides being just R and the distance to the horizon (s). Using the Pythagorean theorem, we can solve for s:Illustration: Rhett AllainNow we just need to plug in our values for R and h to get a distance of 4,657 meters, or about 2.89 miles. Of course, if you increase your distance from the surface (h), then you can also see farther. But…