一个圆锥，它的底面直径和高均为2R,求这个圆锥的表面积和体积？求答案 已知圆锥的表面积为am2，且它的侧面展开图是一个半圆，求这个...
\u4e00\u4e2a\u5706\u9525\uff0c\u5b83\u7684\u5e95\u9762\u76f4\u5f84\u548c\u9ad8\u5747\u4e3a2R\uff081\uff09\u6c42\u8fd9\u4e2a\u5706\u9525\u7684\u8868\u9762\u79ef\u548c\u4f53\u79ef\uff1b\uff082\uff09\u5728\u8be5\u5706\u9525\u5185\u4f5c\u4e00\u5185\u63a5\u5706\u67f1\uff0c\u5f53\u5706\u67f1\u89e3\uff1a\uff081\uff09\u4f53\u79ef\uff1a13sh=13\u03c0r2h=23\u03c0R3\uff0e\uff082\uff09\u5982\u56fe\uff0c\u4f5c\u51fa\u5706\u9525\u7684\u8f74\u622a\u9762\uff0c\u8bbe\u5706\u67f1\u7684\u9ad8\u4e3ah\uff0c\u5e95\u9762\u534a\u5f84\u4e3ar\uff080\uff1cr\uff1cR\uff09\uff0c\u4f53\u79ef\u4e3aV\uff0c\u5219h2R=R?rR\uff0c\u2234h=2\uff08R-r\uff09\uff0c\u2234V=\u03c0r2h=2\u03c0r2\uff08R-r\uff09\uff0e=2\u03c0Rr2-2\u03c0r3\uff0e\u2234V\u2032=4\u03c0Rr-6\u03c0r2\uff0c\u4ee4V\u2032=0\uff0c\u5f97r=23R\uff0c\u2234\u5f53r=23R\u65f6\uff0c\u5706\u67f1\u7684\u4f53\u79efV\u53d6\u5f97\u6700\u5927\u503c\uff0c\u6b64\u65f6\u5706\u67f1\u7684\u9ad8h=2\uff08R-23R\uff09=23R\uff0e\u5706\u67f1\u7684\u4f53\u79efV\u7684\u6700\u5927\u503c\uff1a827\u03c0R3\uff0e
\u8bbe\u5706\u9525\u7684\u5e95\u9762\u7684\u534a\u5f84\u4e3ar\uff0c\u5706\u9525\u7684\u6bcd\u7ebf\u4e3al\uff0c\u5219\u7531\u03c0l=2\u03c0r\u5f97l=2r\uff0c\u800cS=\u03c0r2+\u03c0r?2r=a\uff0c\u53733\u03c0r2=a\uff0c\u2234r=3\u03c0a3\u03c0\uff0c\u5373\u76f4\u5f84\u4e3a23\u03c0a3\u03c0\uff0e
体积：V=1/3SH=1/3*1/2*π*r^2*h=1/3*πR3表面积：S=S底+S侧=πR^2+πLR（L是圆锥的侧长，R是圆锥半径）=πR^2+根号5πR^2=根号5 +1πR的平方 L可以用勾股定理计算
表面积：3.14R*R+6.28*R*R=9.42R*R
体积：3.14R*R*2R/3=2.093RRR
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