已知三棱柱三棱柱三个侧面都是矩形若底面的一边长为2cm,另两边长为3cm侧棱长为4cm求它的体积和表面积。2. 高中数学题
\u5df2\u77e5\u4e09\u68f1\u67f1\u5e95\u9762\u7684\u4e00\u8fb9\u957f\u4e3a2CM\uff0c\u53e6\u4e24\u8fb9\u957f\u90fd\u4e3a3CM\uff0c\u4fa7\u68f1\u957f\u4e3a4CM\uff0c\u4e14\u4e0e\u5e95\u9762\u621045\u5ea6\u89d2\uff0c\u6c42\u5b83\u7684\u4f53\u79ef\u3002\u8981\u8fc7\u7a0b\u5e95\u9762\u662f\u4e00\u4e2a\u7b49\u8170\u4e09\u89d2\u5f62,\u8fb9\u957f\u662f2,3,3.
\u6240\u4ee5\u5f88\u5bb9\u6613\u901a\u8fc7\u4f5c\u5e95\u8fb9\u4e0a\u7684\u9ad8\u7684\u65b9\u6cd5\u6c42\u51fa\u9762\u79ef\u662f2\u6839\u53f72.
\u9ad8\u5176\u5b9e\u5c31\u662f\u4fa7\u68f1\u7684\u957f\u5ea6\u4e58\u4ee5\u5b83\u4e0e\u5e95\u9762\u5939\u89d2\u7684\u6b63\u5f26,
\u4e5f\u5c31\u662f4*sin(45)=2\u6839\u53f72.
\u6240\u4ee5:\u7531\u67f1\u4f53\u7684\u4f53\u79ef\u516c\u5f0f,\u4f53\u79ef=\u5e95\u9762\u79ef*\u9ad8,
\u5f97\u5230:\u4f53\u79ef=8\u7acb\u65b9\u5398\u7c73.
20.\u8fc7F\u505aAB\u7684\u5e73\u884c\u7ebf\u4ea4BC\u4e8eE\uff0c\u8fc7E\u505aCD\u7684\u5e73\u884c\u7ebf\u4ea4BD\u4e8eH\uff0c\u8fc7H\u505aBA\u7684\u5e73\u884c\u7ebf\u4ea4AD\u4e8eG\uff0c\u8fde\u63a5GF\uff0cAF/FC=BE/EC=BH/HD=AG/GD\uff0c\u5219FG\u2225CD\uff0cFG\u2225EH\uff0c\u2235FE\u2225AB\u2225GH\uff0c\u2234FEHG\u4e3a\u5e73\u884c\u56db\u8fb9\u5f62\u3002
21.\uff081\uff09\u8fde\u63a5AC'\u3001AB'\uff0cM\u4e3aA'B\u7684\u4e2d\u70b9\uff0c\u2235ABB'A'\u4e3a\u957f\u65b9\u5f62\uff0c\u2234AB'\u4e0eA'B\u4ea4\u4e8eM\uff0c\u5728\u25b3AB'C'\u4e2dM\u3001N\u4e3a\u4e24\u8fb9\u7684\u4e2d\u70b9\uff0c\u5219MN\u2225AC'\uff0c\u2235AC'\u662f\u5e73\u9762A'ACC'\u4e2d\u7684\u76f4\u7ebf\uff0c\u2234MN\u2225\u5e73\u9762A'ACC'\uff1b
\uff082\uff09\u8fde\u63a5BN\uff0cBC=B'C'=2\uff0cB'N=NC'=A'N=1\uff0cA'A=B'B=C'C=1\uff0c\u5219BN=CN=\u221a2\uff0cA'B=A'C=\u221a3\uff0c\u5728\u25b3A'NB\u548c\u25b3A'NC\u4e2d\u5206\u522b\uff1aA'N²+BN²=A'B²\uff0cA'N²+CN²=A'C²\uff0c\u25b3A'NB\u548c\u25b3A'NC\u4e3a\u76f4\u89d2\u25b3\uff0cA'N\u22a5BN\uff0cA'N\u22a5CN\uff0c\u5219A'N\u22a5\u5e73\u9762BCN\uff0cA'N\u4e3a\u4e09\u68f1\u9525A'-BCN\u7684\u9ad8\uff0c\u5728\u25b3A'BN\u4e2d\u8fc7M\u505aBN\u7684\u5782\u7ebf\u4ea4\u4e8eD\uff0cMD\u2225A'N\uff0c\u5219MD\u22a5\u5e73\u9762BCN\uff0cMD\u4e3a\u4e09\u68f1\u9525M-BCN\u7684\u9ad8\uff0cMD=A'N/2\uff0c\u4e09\u68f1\u9525A'-MNC\u7684\u4f53\u79ef=\u4e09\u68f1\u9525A'-BCN\u7684\u4f53\u79ef-\u4e09\u68f1\u9525M-BCN\u7684\u4f53\u79ef\uff0c\u25b3BCN\u4e3a\u76f4\u89d2\u25b3\uff0c\u25b3BCN\u7684\u9762\u79ef=1\uff0c\u5219\u4e09\u68f1\u9525A'-MNC\u7684\u4f53\u79ef=1/3-1/6=1/6.
=3*4+3*4+2*4+2*2√2/2*2=32+4√2
体积V=底面积*高
=2√2*4
=8√2
2https://gss0.baidu.com/94o3dSag_xI4khGko9WTAnF6hhy/zhidao/pic/item/f636afc379310a556bf3cb85b54543a9832610ef.jpg
1，如图所示：
2，明天再答。
我也正需要
绛旓細1鍏ㄩ潰绉疭=涓変釜渚闈㈢Н+涓婁笅涓や釜搴曢潰绉 =3*4+3*4+2*4+2*2鈭2/2*2=32+4鈭2 浣撶НV=搴曢潰绉*楂 =2鈭2*4 =8鈭2 2http://a.hiphotos.baidu.com/zhidao/pic/item/f636afc379310a556bf3cb85b54543a9832610ef.jpg
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