70?-130?

Greek mathematician and astronomer who is considered the founder of spherical trigonometry, which was later used by Ptolemy in his Algamest. From Ptolemy we know that Menelaus made astronomical observations in Rome in A.D. 98, and used these to calculate the rate of movement of the equinox. He may have written on spherical propositions, the weight and distribution of objects, geometry, the triangle, and possibly on mechanics, but only his work on spherical trigonometry, the Sphaerica, survives.