已知圆锥的底面半径是3cm,高是4cm,则这个圆锥的侧面展开图的面积是
\u5df2\u77e5\u5706\u9525\u7684\u5e95\u9762\u534a\u5f84\u662f3\uff0c\u9ad8\u662f4\uff0c\u5219\u8fd9\u4e2a\u5706\u9525\u7684\u4fa7\u9762\u5c55\u5f00\u56fe\u7684\u9762\u79ef\u662f______\u2235\u5706\u9525\u7684\u5e95\u9762\u534a\u5f84\u662f3\uff0c\u9ad8\u662f4\uff0c\u2234\u5706\u9525\u7684\u6bcd\u7ebf\u957f\u4e3a5\uff0c\u2234\u8fd9\u4e2a\u5706\u9525\u7684\u4fa7\u9762\u5c55\u5f00\u56fe\u7684\u9762\u79ef\u662f\u03c0\u00d73\u00d75=15\u03c0\uff0e\u6545\u7b54\u6848\u4e3a15\u03c0\uff0e
\u5e95\u9762\u534a\u5f84\u4e3a3cm\uff0c\u5219\u5e95\u9762\u5468\u957f=6\u03c0cm\uff0c\u4fa7\u9762\u9762\u79ef=12\u00d76\u03c0\u00d74=12\u03c0cm2\uff0e
| 15π． 绛旓細瑙鍦嗛敟鐨浣撶НV=1/3螤r^2h=1/3脳3.14脳3^2脳8=75.36绔嬫柟鍘樼背銆 绛旓細鐢卞渾閿ョ殑浣撶Н鍏紡锛歏=(1/3)蟺r^2h锛堝叾涓鏄渾鍛ㄧ巼锛宺琛ㄧず搴曢潰鍦嗙殑鍗婂緞锛h琛ㄧず鍦嗛敟鐨勯珮锛夛紝鍙緱锛氳繖涓渾閿ョ殑浣撶Н=(1/3)x3.14x3^2x10 =3.14x30 =92.4绔嬫柟鍘樼背銆 绛旓細姣嶇嚎涓簂锛鍗婂緞涓r锛岄珮涓篽 鏍规嵁鍕捐偂瀹氱悊鈭歭=r^2+h^2=鈭(9+27)=6鍦嗗績瑙=(2蟺r/2蟺l)*360掳=180掳 鍦嗛敟鐨琛ㄩ潰绉=搴曢潰绉+渚ч潰绉 S=蟺r^2+蟺rl=27蟺 绛旓細鍦嗘煴鐨勪綋绉細3.14脳3 2 脳3锛 =3.14脳9脳3锛 =84.78锛堢珛鏂瑰帢绫筹級锛 鐢遍鎰忓彲鐭ワ細鍦嗛敟涓庡渾鏌辩瓑搴曠瓑楂橈紝 鍒欒繖涓鍦嗛敟浣鐨勪綋绉槸杩欎釜鍦嗘煴浣撶殑 1 3 锛 鍗筹紝84.78脳 1 3 =28.26锛堢珛鏂瑰帢绫筹級锛 鏁呯瓟妗堜负锛84.78绔嬫柟鍘樼背锛28.26绔嬫柟鍘樼背锛 绛旓細搴曢潰鍦嗗懆闀夸负 2*3*pi =6pi 涔熷氨鏄睍寮闈㈢殑鎵囧舰寮ч暱 鍏ㄩ潰绉=搴曢潰绉+渚ч潰绉 =pi*r^2 + 1/2 *寮ч暱*姣嶇嚎闀 =9pi+ 1/2 *6pi * 鏍瑰彿涓(3^2+4^2)=9pi+15pi =24pi 绛旓細1/3x3x3x3.14x1=9.42锛堢珛鏂瑰帢绫筹級绛旓細瀹冪殑浣撶Н鏄9.42 绔嬫柟鍘樼背 绛旓細4绫=400鍘樼背 1/3脳3²蟺脳400=3768绔嬫柟鍘樼背 骞虫柟鍘樼背鏄潰绉殑鍗曚綅 绛旓細鍦嗛敟浣撶Н=1/3*搴曢潰绉*楂=1/3*3.14*3²*6=56.52绔嬫柟鍘樼背 绛旓細绛旓細10锛3cm锛绾︿负锛3.33銕濄傝В锛鍦嗛敟浣撶Н鍏紡锛歷=1/3(s*h)锛1/3(蟺r锛2锛奾)h锛3V锛弒 锛坴锛氫綋绉紝s锛氬簳闈㈢Н锛宧锛氶珮锛塖=蟺r锛2=蟺脳3锛2锛9蟺锛28.26锛埾鍙3.14锛塰锛3脳31.4梅28.26 锛10锛3 鈮3.33cm銆 绛旓細璇曢绛旀锛渚ч潰灞曞紑鍥炬墖褰㈢殑寮ч暱鏄6蟺锛岃姣嶇嚎闀挎槸r锛屽垯12脳6蟺•r=15蟺锛岃В寰楋細r=5锛屾牴鎹嬀鑲″畾鐞嗗緱鍒帮細鍦嗛敟鐨勯珮=52-32=4cm锛庢晠绛旀涓4cm锛 本站交流只代表网友个人观点，与本站立场无关 |
