1. The problem statement, all variables and given/known data An optical telescope with a 12mm eyepiece makes the Moon appear to have an angular diameter of 30 degrees. What is the focal length of the telescope's objective? 2. Relevant equations magnification=focal length of objective/focal length of eyepiece 3. The attempt at a solution I'm not sure what I'm able to do given a diameter and angular diameter in order to get the magnification and focal length of the eyepiece as needed.