Menelaus of Alexandria

Some Notes on Menelaus.
His work on spherical geometry furthers into Non Euclidian Geometry.  Geodesic, a straight line is a small segment of a large circle who has a center.  Modern aviation, airplanes use this knowledge to fly.  This is how commercial airplanes fly.  (I learned this fact from a book call 'Is God a Mathematician'? 
Mathematician began to see fault in Euclid's geometry because of his proposition for Parallel line was long and clumsy.  In spherical geometry, the parallel lines do not extend for ever in parallels.  They come to a point.  This is why there is a distinction between spherical geometry and plane geometry.  Look at the globe.  The meridian comes to a point at the North and South Poles.