举报
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2、 V=πR^2*L/4=3.14*1^2*20/4 =15.7(dm^3) S=2*(πR^2/4)+2*(1*20)+(2πR/4)*20 =2*3.14*1^2/4+2*1*20+2*3.14*1*20/4 =72.97(dm^2) 3、 2R+2πR=16.56 解,R=2(dm) 高为4R=8(dm) 则其体积为 V=πR^2*h=3.14*(16.56/(2(1+3.14)))^2*(4*(16.56/(2(1+3.14)))) =3.14*2*2*8 =32π=100.48(dm^3)