已知圆台的上、下底面半径分别是2、6,且侧面面积等于两底面面积之和.(1)求该圆台母线的长;(2)求该
\u5df2\u77e5\u5706\u53f0\u7684\u4e0a\u4e0b\u5e95\u9762\u534a\u5f84\u5206\u522b\u662f2\u548c5,\u4e14\u4fa7\u9762\u9762\u79ef\u7b49\u4e8e\u4e24\u5e95\u9762\u9762\u79ef\u4e4b\u548c,\u6c42\u8be5\u5706\u53f0\u7684\u6bcd\u7ebf\u957f\u2026\u5982\u56feABDC\u662f\u5706\u53f0\u4fa7\u9762\u5c55\u5f00\u56fe\u3002\u5f27AB\uff1d10\u03c0.\u5f27CD\uff1d4\u03c0.
\u4ece\u800c\u53ef\u8bbeOD\uff1d2x. DB\uff1d3x,
S\uff08ABDC\uff09\uff1d5x\u00d710\u03c0/2-2x\u00d74\u03c0/2\uff1d\u4e24\u5e95\u9762\u9762\u79ef\u4e4b\u548c\uff1d25\u03c0+4\u03c0
\u89e3\u5f97\uff1ax\uff1d29/21. \u6bcd\u7ebf\u957f\uff1dDB\uff1d3x\uff1d29/7\uff08\u957f\u5ea6\u5355\u4f4d\uff09
.
\u5706\u53f0\u4fa7\u9762\u79efS=\u03c0\uff08r+R)*l (R\u4e3a\u4e0a\u5e95\u534a\u5f84\uff0cr\u4e3a\u4e0b\u5e95\u534a\u5f84\uff0cl\u4e3a\u6bcd\u7ebf\uff09
\u5706\u53f0\u4f53\u79efV=\u03c0*h*(R^2+r^2+R*r)/3 (h\u4e3a\u9ad8)
\u7531\u9898\u610f\u6709\uff1a
1; S=8\u03c0l=4\u03c0+36\u03c0
\u5f97l=5
2; \u5148\u6c42\u9ad8\uff0c\u6784\u9020\u76f4\u89d2\u4e09\u89d2\u5f62\uff0c\u659c\u8fb9\u4e3al=5\uff0c\u4e00\u76f4\u89d2\u8fb9\u4e3ar-R=6-2=4\uff0c\u6240\u4ee5\u53e6\u4e00\u76f4\u89d2\u8fb9h=3\uff08\u56fe\u4e0d \u7528 \u753b\u5427\uff09
\u6240\u4ee5V=\u03c0*3*\uff084+36+12\uff09/3=52\u03c0
∴8πl=40π,l=5.
∴该圆台的母线长为5;
(2)设圆台的高为h,由勾股定理可得h=
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