Dysnomian

This is an annoying question for my maths assignment that I can't seem to find a place to get an answer. Basically, we have been asked to find the modern measurement to the radius of the moon (1 737.4 kilometers) and how it was obtained, then to compare it to Hippachus' method using trigonometry. But what was that method that has found the most accurate modern measurement? Info and links to sites with info would be much appreciated.