$$S=\frac{1}{2}R^2n\sin \frac{360^\circ}{n},$$ $$R=\frac{a}{2\sin \frac{180^\circ}{n}},\;\;r=\frac{a}{2\text{tg } \frac{180^\circ}{n}}.$$

Вид правильного многоугольника$$\alpha$$$$R$$$$r$$Сумма углов
$$60^\circ$$ $$\frac{a\sqrt 3}{3}$$ $$\frac{a\sqrt 3}{6}$$ $$180^\circ$$
$$90^\circ$$ $$\frac{a\sqrt 2}{2}$$ $$\frac{a}{2}$$ $$360^\circ$$
$$120^\circ$$ $$a$$ $$\frac{a\sqrt 3}{2}$$ $$720^\circ$$


2010-12-19 • Просмотров [ 1552 ]