20/10/27 09:20:16.58 /9MkT2sb.net
n L/na S/正n角形 S/外接長方形
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3 1.396263 5.83680 0.84247
4 1.34076 4.14159 0.732137
6 1.30273 3.41840 0.740105
8 1.28973 3.22144 0.744056
12 1.280537 3.09440 0.74724
16 1.27734 3.052344 0.748424
18 1.276477 3.04120 0.74875
24 1.27506 3.02303 0.74929
∞ 1.27324 3.0 0.75
(4/π)