组合(复合)图形的形心 由n个规则形状组成的图形A=∑A ∫4=∑j4=2 ∫al-=∑l=∑ ∑z4由 n 个规则形状组成的图形 y C z z y = = n i A Ai 1 = = = = = n i c i i n i Sz ydA yi dA y A 1 1 组合(复合)图形的形心 = = = = n i i n i ci i y c A z A A S z 1 1 = = = = n i i n i ci i z c A y A A S y 1 1 = = = = = n i c i i n i Sy zdA zi dA z A 1 1