小学平面图形公式大全：

长方形的周长=（长+宽）×2

正方形的周长=边长×4

长方形的面积=长×宽

正方形的面积=边长×边长

三角形的面积=底×高÷2

平行四边形的面积=底×高

梯形的面积=（上底+下底）×高÷2

直径=半径×2，半径=直径÷2

圆的周长=圆周率×直径= 圆周率×半径×2

圆的面积=圆周率×半径×半径

扇形的面积＝圆周率×半径²×（圆心角/360）

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