把一张圆形纸片剪成一个近似的长方形，已知这个长方形的周长是33.12分米，求圆的面积？ 将一个圆剪拼成一个近似的长方形,已知这个长方形的周长是33....
\u5c06\u4e00\u4e2a\u5706\u526a\u62fc\u6210\u4e00\u4e2a\u8fd1\u4f3c\u7684\u957f\u65b9\u5f62\uff0c\u5df2\u77e5\u8fd9\u4e2a\u957f\u65b9\u5f62\u7684\u5468\u957f\u662f33.12\u5206\u7c73\uff0c\u89e3\u7b54\uff1a\u5706\u7684\u9762\u79ef\u4e3a50.24\u5e73\u65b9\u5398\u7c73\u3002
\u89e3\u6790\uff1a\u8fd9\u4e2a\u957f\u65b9\u5f62\u7684\u5468\u957f=\u5706\u7684\u5468\u957f+\u76f4\u5f84=3.14\u00d7\u76f4\u5f84+\u76f4\u5f84=\u76f4\u5f84\u00d7\uff083.14+1\uff09
\u6240\u4ee5\uff0c\u5706\u7684\u76f4\u5f84=33.12\u00f7\uff083.14+1\uff09=8\uff08\u5206\u7c73\uff09
\u5706\u7684\u9762\u79ef=3.14\u00d7\uff088\u00f72\uff09²=50.24\uff08\u5e73\u65b9\u5206\u7c73\uff09
\u6269\u5c55\u8d44\u6599\uff1a
\u5728\u540c\u5706\u6216\u7b49\u5706\u4e2d\uff0c\u5982\u679c\u4e24\u4e2a\u5706\u5fc3\u89d2\uff0c\u4e24\u4e2a\u5706\u5468\u89d2\uff0c\u4e24\u7ec4\u5f27\uff0c\u4e24\u6761\u5f26\uff0c\u4e24\u6761\u5f26\u5fc3\u8ddd\u4e2d\u6709\u4e00\u7ec4\u91cf\u76f8\u7b49\uff0c\u90a3\u4e48\u4ed6\u4eec\u6240\u5bf9\u5e94\u7684\u5176\u4f59\u5404\u7ec4\u91cf\u90fd\u5206\u522b\u76f8\u7b49\u3002
\u540c\u5706\u6216\u7b49\u5706\u4e2d\uff0c\u76f8\u7b49\u7684\u5f27\u6240\u5bf9\u7684\u5706\u5468\u89d2\u7b49\u4e8e\u5b83\u6240\u5bf9\u7684\u5706\u5fc3\u89d2\u7684\u4e00\u534a\uff08\u5706\u5468\u89d2\u4e0e\u5706\u5fc3\u89d2\u5728\u5f26\u7684\u540c\u4fa7\uff09\uff1b\u5982\u679c\u4e00\u6761\u5f27\u7684\u957f\u662f\u53e6\u4e00\u6761\u5f27\u76842\u500d\uff0c\u90a3\u4e48\u5176\u6240\u5bf9\u7684\u5706\u5468\u89d2\u548c\u5706\u5fc3\u89d2\u662f\u53e6\u4e00\u6761\u5f27\u76842\u500d\u3002
\u89e3\uff1a\u8bbe\u957f\u65b9\u5f62\u7684\u957f\u4e3am\u5bbd\u4e3ar\uff0c\u5219\uff1a33.12=2(r+m)
\u800c\uff1a\u7531\u9898\u610f\u77e52\u03c0r=2m,
\u5373\uff1am=\u03c0r
\u6240\u4ee5\uff1a33.\u00b712=2\uff08r+\u03c0r)
\u6c42\u5f97\uff1ar=4\u03c0
\u6240\u4ee5\uff1a\u5143\u7684\u9762\u79ef\u4e3a\u03c0r²=16\u03c0³\u2248495\uff08dm²\uff09
\u5728\u4e00\u4e2a\u5e73\u9762\u5185\uff0c\u4e00\u52a8\u70b9\u4ee5\u4e00\u5b9a\u70b9\u4e3a\u4e2d\u5fc3\uff0c\u4ee5\u4e00\u5b9a\u957f\u5ea6\u4e3a\u8ddd\u79bb\u65cb\u8f6c\u4e00\u5468\u6240\u5f62\u6210\u7684\u5c01\u95ed\u66f2\u7ebf\u53eb\u505a\u5706\u3002
\u5728\u540c\u4e00\u5e73\u9762\u5185\u5728\uff0c\u5230\u5b9a\u70b9\u7684\u8ddd\u79bb\u7b49\u4e8e\u5b9a\u957f\u7684\u70b9\u7684\u96c6\u5408\u53eb\u505a\u5706\u3002\u5706\u53ef\u4ee5\u8868\u793a\u4e3a\u96c6\u5408{M||MO|=r},\u5706\u7684\u6807\u51c6\u65b9\u7a0b\u662f(x - a) 2 + (y - b) 2 = r 2\u3002\u5176\u4e2d\uff0c(a , b)\u662f\u5706\u5fc3\uff0cr \u662f\u534a\u5f84\u3002
\u5706\u5f62\u662f\u4e00\u79cd\u5706\u9525\u66f2\u7ebf\uff0c\u7531\u5e73\u884c\u4e8e\u5706\u9525\u5e95\u9762\u7684\u5e73\u9762\u622a\u5706\u9525\u5f97\u5230\u3002
\u5706\u662f\u4e00\u79cd\u51e0\u4f55\u56fe\u5f62\u3002\u6839\u636e\u5b9a\u4e49\uff0c\u901a\u5e38\u7528\u5706\u89c4\u6765\u753b\u5706\u3002 \u540c\u5706\u5185\u5706\u7684\u76f4\u5f84\u3001\u534a\u5f84\u957f\u5ea6\u6c38\u8fdc\u76f8\u540c\uff0c\u5706\u6709\u65e0\u6570\u6761\u534a\u5f84\u548c\u65e0\u6570\u6761\u76f4\u5f84\u3002\u5706\u662f\u8f74\u5bf9\u79f0\u3001\u4e2d\u5fc3\u5bf9\u79f0\u56fe\u5f62\u3002\u5bf9\u79f0\u8f74\u662f\u76f4\u5f84\u6240\u5728\u7684\u76f4\u7ebf\u3002 \u540c\u65f6\uff0c\u5706\u53c8\u662f\u201c\u6b63\u65e0\u9650\u591a\u8fb9\u5f62\u201d\uff0c\u800c\u201c\u65e0\u9650\u201d\u53ea\u662f\u4e00\u4e2a\u6982\u5ff5\u3002\u5f53\u591a\u8fb9\u5f62\u7684\u8fb9\u6570\u8d8a\u591a\u65f6\uff0c\u5176\u5f62\u72b6\u3001\u5468\u957f\u3001\u9762\u79ef\u5c31\u90fd\u8d8a\u63a5\u8fd1\u4e8e\u5706\u3002\u6240\u4ee5\uff0c\u4e16\u754c\u4e0a\u6ca1\u6709\u771f\u6b63\u7684\u5706\uff0c\u5706\u5b9e\u9645\u4e0a\u53ea\u662f\u6982\u5ff5\u6027\u7684\u56fe\u5f62\u3002
R＝4分米
圆的面积是3.14×4×4＝50.24平方分米
2πR＋2R＝33.12
R＝4分米
圆的面积是3.14×4×4＝50.24平方分米
0
绛旓細鑻ユ嫾鎴愪竴涓暱鏂瑰舰锛岋紝棣栧厛闇瑕佹妸鍦嗗垎鎴愪袱涓崐鍦嗭紝浠庡渾蹇冨悜鍦嗙殑鍛ㄩ暱杈瑰壀鍑轰竴浜涙墖褰紝瓒婂瓒婂儚闀挎柟褰紝鍗婂緞灏辨槸闀挎柟褰㈢殑瀹斤紝闀挎柟褰鐨勯暱灏辨槸鍦嗗懆闀跨殑涓鍗娿
绛旓細鍛ㄩ暱=6脳(1+3.14)=24.84鍘樼背 涓嶆噦鍙拷闂紝鏈夊府鍔╄閲囩撼锛岃阿璋紒
绛旓細鎶婁竴涓鍦嗗舰绾哥墖鍓鎷兼垚涓涓繎浼肩殑闀鏂瑰舰锛屽垯闀挎柟褰㈢殑鍛ㄩ暱姣斿渾鐨勫懆闀垮2鏉″崐寰勭殑闀垮害銆2鏉″崐寰勯暱6鍘樼背锛屽垯鍗婂緞涓3鍘樼背銆傚垯鍦嗙殑闈㈢Н涓 3.14x3x3 = 28.26 骞虫柟鍘樼背銆
绛旓細鎶婁竴涓鍦嗗舰绾哥墖鍓寮鍚庢嫾鎴涓涓繎浼肩殑闀鏂瑰舰锛岃繖涓暱鏂瑰舰鐨勯暱灏辨槸鍦嗗懆闀跨殑涓鍗婏紝瀹藉氨鏄渾鐨勫崐寰勶紝闀挎柟褰㈢殑鍛ㄩ暱灏辨槸鍦嗙殑鍛ㄩ暱鍔犱笂涓ゆ潯鍗婂緞锛岃繖涓暱鏂瑰舰鐨勫懆闀挎瘮鍦嗙殑鍛ㄩ暱澶6鍘樼背灏辨槸涓ゆ潯鍗婂緞鏄6鍘樼背锛屽渾鐨勫崐寰勫氨鏄6梅2=3鍘樼背锛岄潰绉氨鏄3脳3脳3.14=28.26骞虫柟鍘樼背 ...
绛旓細濡傚浘锛杩戜技鐨勯暱鏂瑰舰ABCD鍙互鐪嬫垚灏嗗乏杈圭殑鍦嗗垎鎴怤浠斤紝鐒跺悗灏嗗皬鍧楅鎴愪竴璧风殑锛屽叾涓彲浠ョ湅鍑篈D=BC=鍗婂緞R锛屽浘涓槸灏嗗渾鍒嗘垚24浠藉緱鍒扮殑锛屽鏋滃垎鎴愭洿澶氫唤锛屽舰鐘舵洿鍍忎釜闀挎柟褰紝鍏朵腑AB+CD=鍦嗙殑鍛ㄩ暱2蟺R锛屽垯鏈夐暱鏂瑰舰鍛ㄩ暱涓2蟺R+2R=8.28锛屽彇蟺涓3.14鍒欐湁R=1锛屽垯鍘熸潵鐨鍦嗗舰绾哥墖鍛ㄩ暱涓2蟺R=6.28鍗...
绛旓細24.84梅2=12.42鍘樼背 闀夸笌瀹界殑鍜岋紝涔熸槸鍗婂緞鍜屽渾鍛ㄩ暱鐨勪竴鍗婄殑鍜 12.42梅锛1+3.14锛=3鍘樼背 杩欐槸鍗婂緞 鍦嗙殑闈㈢Н锛3.14脳3²=28.26骞虫柟鍘樼背
绛旓細杩欎釜鍦嗗舰绾哥墖鐨勯潰绉害鏄1.8058骞虫柟鍘樼背锛屼繚鐣欎袱浣嶅皬鏁版槸1.81骞虫柟鍘樼背銆傝绠楄繃绋嬪涓嬶細鍥犱负闀挎柟褰鐨勯暱锛屼负鍦嗗懆闀跨殑涓鍗婏紱闀挎柟褰㈢殑瀹斤紝涓哄渾鐨勫崐寰勩傝锛氬渾鍗婂緞涓簉 渚濋鎰忓拰宸茬煡锛2r+2蟺r=6.28銆傝В寰楋細r=3.14/(1+蟺)銆1銆佸ぉ鍦嗗湴鏂癸細澶╁渾鍦版柟鏄腑鍥戒紶缁熸枃鍖栨濇兂锛屾湁鍦嗘湁鏂癸紝浠ュ渾涓鸿寖锛岃鐭╂垚...
绛旓細闀挎柟褰㈢殑鍛ㄩ暱鏄瓑浜鍦嗙殑鍛ㄩ暱+2涓崐寰,鍗虫槸16.56cm 鎵浠,鍗婂緞=16.56/(3.14+2)=5鍘樼背 閭ｄ箞闈㈢Н=3.14*5^2=3.14*25=78.5骞虫柟鍘樼背
绛旓細zhi000peng锛屼綘濂斤細鍛ㄩ暱鍙樺ぇ锛岄潰绉笉鍙樸傛嫾鎴愮殑杩戜技闀鏂瑰舰鐨勪袱鏉￠暱鐨勫拰绛変簬鍦嗙殑鍛ㄩ暱锛屼袱鏉″鐨勫拰绛変簬鍦嗙殑鐩村緞锛屽嵆鍛ㄩ暱澧炲姞浜嗕竴鏉＄洿寰鐨勯暱銆
绛旓細淇濈暀涓や綅灏忔暟鏄1.81骞虫柟鍘樼背銆傝绠楄繃绋嬪涓嬶細鍥犱负闀挎柟褰鐨勯暱锛屼负鍦嗗懆闀跨殑涓鍗婏紱闀挎柟褰㈢殑瀹斤紝涓哄渾鐨勫崐寰勩傝锛氬渾鍗婂緞涓簉 渚濋鎰忓拰宸茬煡锛2r+2蟺r=6.28 瑙ｅ緱锛歳=3.14/(1+蟺)鍥犳鍦嗗舰鐨勯潰绉槸锛毾r^2=蟺[3.14/(1+蟺)]^2鈮1.8058锛坈m^2锛夋墍浠ヨ繖涓鍦嗗舰绾哥墖鐨勯潰绉害鏄1.8058骞虫柟鍘樼背 ...
