[填空题]
Eclipses happen on Earth because of an amazing coincidence. Calculate, u,ltdh- :,(-odhxt9hk r1 r-zibxvp / s8 w:f32xju fmb7 mu)jpsing the information inside the Front Cover, the angular diameters (in radians) of the Sun and the Moon, as seen o7fbp fwmu:382j ) jmxun Earth. Sun = $rad$ Moon = $rad$