[填空题]
Eclipses happen on Earyfz ug*q+hmeh6k3 /z7th because ofx4 4lxa7p0dl;k hkb b8 an amazing coincidence. Calculate, using the information inside the Front Cover, the angular diameters (in radians) of the Sun axk8b dpl04xk47l ab h;nd the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$