Is the Earth flat and stationary, or is it curved and rotating? A Maths approach!

Here I explain how the units of the '8 inches per mile squared' assumption are incorrect (a reciprocal length)
Even when these values are multiplied together they became the units of volume, not length!
Throughout I use mathematical calculations, trigonometry (cosine function), spreadsheet calculations and wxMaxima sinusoidal images
These values are compared and contrasted throughout, changing from SI units (metres) to miles to show that the so-called approximation is incorrect
Sources; https://en.wikipedia.org/wiki/Earth_radius
Earth curvature calculations https://earthcurvature.com/
http://wxmaxima-developers.github.io/wxmaxima/index.html