11课弧长及扇形的面积

71212123.,,,,2.135m,10cm.(1),A(2)o,A(3)o,A1ORo2oORnol1o1060o2OAOBCDOCOA=12CDABOA11B1DCC21D1BA1.AB0.1mmAB110oR=40mm23m12o192360o2ooOR2nonO1oonRls:AOB12cm,AOB=120o,AB(0.1cm)AOB(0.1cm2)1.90o2==.2.20cm240c.3.120o6A.3B.4C.5D.6P1341213.1021AB=OABC()1234()()1232.135m