103.4.22補充
3.
Let M be a point in the interior(strictly) of a n-regular polygon with sides of length a. Let \( d_1, \ldots, d_n \) be the distance between Mand the different sides of the polygon. Prove that \( \displaystyle \frac{1}{d_1}+\frac{1}{d_2}+\ldots+\frac{1}{d_n}>\frac{2\pi}{a} \)