I'm not trying to say who is right and who is wrong. I just find that if flat-earthers can't even get basic math right, how can they be right about much else?If you want me to say you are right and I am wrong, due to the accuracy and deviation of my simplistic, although applicable, equation, then OK I give. You are right, I am wrong.
I have made the grave error of agreeing with people like this:
You use the Pythagorean theorem. If you are at a point P on the earth's surface and move tangent to the surface a distance of 1 mile then you can form a right angled triangle as in the diagram. Using the theorem of Pythagoras a2 = 39632 + 12 = 15705370 and thus a = 3963.000126 miles. Thus your position is 3963.000126 - 3963 = 0.000126 miles above the surface of the earth. 0.000126 miles = 1252800.000126 = 7.98 inches. Hence the earth's surface curves at approximately 8 inches per mile.
Note that the person presenting this states "approximately" 8 inches per mile. This is the point of the error in my calculation. A sphere cannot have a curve of a certain number of units per mile that changes as the distance increases. The curve of a sphere is constant. If I were able to find the exact curve per mile, I could calculate it by squaring the distance. Not for area but for the exponential increase in the curve.
No, you couldn't. That is simply not how math works. You can't just decide that you are going to square a number "for the exponential increase in the curve" and not for area. That's just arbitrary.
And the first two are not correct, although the second is better than the first, for the following reasons:Here are three methods that can be used to calculate the magic number. Check this site. They show Zetetic Astronomy, Pythagorean Theorem and Trigonometry. http://flatvsround.blogspot.ca/2015/10/how-to-calculate-earths-curvature.html
1) As I have been pointing out, units matter. When multiplying, dividing, adding, or subtracting numbers with units, the units also have to be taken into account to ensure that the answer has the correct units one is looking for. In the first equation, the one you are fond of, we have: miles * miles * inches / inches / feet. That means the answer to the equation has the units: miles²ft, which doesn't even make sense. Of course, one could convert the inches to miles first but then we would get: miles * miles * miles, which, as I have previously stated, gives us miles³ (volume).
When you do the second and third examples, they have: miles - miles. The answer therefore has the unit: miles, which is what we are looking for. That makes perfect sense.
2) Look closely at the difference of the distance actually being calculated between the first two equations and the third. In the first two, the distance is normal to the surface of the earth at the point, which is not what we're trying to calculate. In the third, the distance we are calculating is normal to the tangency of the viewpoint. That is what we want--the vertical drop from our view.
3) I hate to point it out again, but the first equation utterly fails at a distance equal to the radius of the earth, whereas the third does not. The second fails as well. That means the first and second equations can approximate up to a point but ultimately rely on improper math.