When building location-based web applications, developers usually default to the Haversine formula to calculate the distance and bearing between two GPS coordinates. For most apps, assuming the Earth is a perfect sphere is "good enough." But what if you are building an application where absolute precision is non-negotiable? While building Quranbookk's Qibla Finder —a web application that helps Muslims worldwide find the exact direction of the Kaaba in Mecca—I quickly realized that stand...