扇形 Circular sector

（重定向自Circle sector）

扇形指圆上被两条半径和半径所截之一段弧所围成的图形。因形状如一把扇子而得名。

扇形的圆心角∝面积∝弧长。

α单位为α°(度)

如α单位为弧度「弪」

单词	Circle sector
释义	Circle sector 中文百科扇形 Circular sector （重定向自Circle sector）扇形指圆上被两条半径和半径所截之一段弧所围成的图形。因形状如一把扇子而得名。扇形的圆心角∝面积∝弧长。面积： $A = \pi r^2 \cdot \frac{\alpha}{360^\circ}$ 弧长： $b = 2 \pi r \cdot \frac{\alpha}{360^\circ}$ α单位为α°(度) 如α单位为弧度「弪」面积： $A = \frac {\alpha r^2} {2}$ 弧长： $b = \alpha r$ 英语百科 Circular sector 扇形（重定向自Circle sector） A circular sector or circle sector (symbol: ⌔), is the portion of a disk enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector. In the diagram, θ is the central angle in radians, $r$ the radius of the circle, and $L$ is the arc length of the minor sector.
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Circle sector