解:设小扇形的母线长为x,已知圆台上底面半径为r1,下底面半径为r2,扇环的母xl由相似三角形得:xrrlr1s2x2rrr221小12x1lr;r2r11;111lr2lr1r2l;1xl2ls大2r22rr2r2r2r11r2lr1r2llr1lr2S扇环s大s小r2r2r1r2r1lr12s上r12s下r2222S圆台s上s下S扇环r1r2lr1lr2r1r2lr1lr222圆台的表面积 参照圆柱和圆锥的侧面展开图,试想象圆台的侧面展开图是什么 . 2r1rO1l2r2r2O 圆台的侧面展开图是扇环 S圆台表面积(rrrlrl) 22 本文来源:https://www.wddqw.com/doc/51a501e648d7c1c709a14544.html