解法二:)、分割图形及建立坐标系,如图所示 A=800mm2,2a=0,y.=0. A2=1100mm2,2e2=-35mm,y.2=60mm 2)、求形心 :气∑4-4+42 A A1+A2 8 -35×1100 =-20.3(mm) 20.3;B4.7) 10×110+80×10 ∑4a=4ya+4y2 80 A A1+A2 60×1100 =34.7(mm) 10×110+80×10 99 80 10 20.3( ) 10 110 80 10 35 1100 = − mm + − = c(-20.3;34.7) 解法二:1)、分割图形及建立坐标系,如图所示 z y C2 C1 800 , 0, 0. 1 1 2 A1 = mm zc = yc = A 1100m m , zc2 35m m, yc2 60m m 2 2 = = − = 2)、求形心 34.7( ) 10 110 80 10 60 1100 = mm + = 1 2 1 1 2 2 A A A z A z A A z z i ci c c c + + = = 1 2 1 1 2 2 A A A y A y A A y y i ci c c c + + = =