Уравнения Площади Сектора (LaTeX)
                    \[Sector\, area = circle\, area \times angular\, ratio\]
                    \[= \pi \times radius^2 \times {\theta(°) \over 360}\]
                    \[= \pi \, R^2 \times {\theta(°) \over 360}\]
                    \[Sector\, area = {radius^2 \over 2} \times \theta_{rad}\]
                    \[= {R^2 \over 2} \times \theta_{rad}\]