Розрахунок: lxt81H - 1
S =
* R^2* n* sin( )
S = * R^2* n* sin( )$$S$$ = $$\frac{1}{2}\cdot R^{2}\cdot n\cdot sin(\frac{360}{n})$$ S = 4* R^2* cos( )* cos( )* cos( )* n* sin( )$$S$$ = $$4\cdot R^{2}\cdot cos(\frac{180}{n})\cdot cos(\frac{45}{n})\cdot cos(\frac{90}{n})\cdot n\cdot sin(\frac{45}{n})$$