[填空题]
Eclipses happen on Earth because oubwj37b1f6 xp e0 ph..xz *epkf an amazing coincidence. Cal5u2 wykko1 pmurb te+665vzm8culate, using the information inside tuw+1r58vp62km keuo5z6t m ybhe Front Cover, the angular diameters (in radians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$