一个圆的周长314cm，面积是多少 一个半圆的周长是10.28cm，面积是多少
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\u89e3\uff1a\u56e0\u4e3a\u5706\u7684\u534a\u5f84=10\u5398\u7c73\uff0c
\u90a3\u4e48\u5706\u7684\u76f4\u5f84=2x\u534a\u5f84=2x10\u5398\u7c73=20\u5398\u7c73\uff0c
\u5706\u7684\u5468\u957f=2x\u03c0x\u534a\u5f84=2x3.14x10\u5398\u7c73=62.8\u5398\u7c73\uff0c
\u5706\u7684\u9762\u79ef=\u03c0x\u534a\u5f84x\u534a\u5f84=3.14x10\u5398\u7c73x10\u5398\u7c73=314\u5e73\u65b9\u5398\u7c73
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1\u3001\u5706\u7684\u76f8\u5173\u6027\u8d28
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\uff082\uff09\u5706\u5fc3\u89d2\u8ba1\u7b97\u516c\u5f0f\u4e3a\uff0c\u03b8=(L/2\u03c0r)\u00d7360\u00b0=180\u00b0L/\u03c0r=L/r(\u5f27\u5ea6)\u3002
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2\u3001\u5706\u7684\u76f8\u5173\u8ba1\u7b97\u516c\u5f0f
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\uff082\uff09\u5706\u7684\u9762\u79ef\u516c\u5f0f
\u5706\u7684\u9762\u79ef=\u03c0*\u5706\u7684\u534a\u5f84*\u5706\u7684\u534a\u5f84
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\u53c2\u8003\u8d44\u6599\u6765\u6e90\uff1a\u767e\u5ea6\u767e\u79d1-\u5706
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2\u03c0r2+2r=10.28\uff0c
\u03c0r+2r=10.28\uff0c
3.14r+2r=10.28\uff0c
5.14r=10.28\uff0c
5.14r\u00f75.14=10.28\u00f75.14\uff0c
r=2\uff1b
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3.14\u00d722\u00f72\uff0c
=3.14\u00d74\u00f72\uff0c
=6.28\uff08\u5e73\u65b9\u5398\u7c73\uff09\uff0e
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直径就是 100 厘米，
半径就是 50 厘米，
3.14 X 50 X 50 = 7850，
圆的面积就是 7850 平方厘米，
绛旓細2500脳3.14=7850
绛旓細鍦嗙殑鍛ㄩ暱 314 鍘樼背锛岀洿寰勫氨鏄 100 鍘樼背锛屽崐寰勫氨鏄 50 鍘樼背锛3.14 X 50 X 50 = 7850锛屽渾鐨勯潰绉氨鏄 7850 骞虫柟鍘樼背锛
绛旓細鍏堟眰鍗婂緞锛314梅3.14梅2=50锛堝帢绫筹級鍐嶆眰闈㈢Н锛3.14脳锛50脳50锛=7850锛堝钩鏂瑰帢绫筹級锛堣鏄庯細50脳50 鏄寚鍗婂緞鐨勫钩鏂癸級鏂规硶鏄細鍗婂緞=鍦嗙殑鍛ㄩ暱梅鍦嗗懆鐜嚸2 鍦嗙殑闈㈢Н=鍦嗗懆鐜嚸楀崐寰劽楀崐寰
绛旓細2蟺r=314 鎵浠=50 鎵浠=蟺r^2=2500*3.14=7850(cm^2)
绛旓細鍗婂緞=314梅3.14梅2=50鍘樼背 闈㈢Н=50脳50脳3.14=7850骞虫柟鍘樼背 涓嶆噦鍙拷闂紝鏈夊府鍔╄閲囩撼锛岃阿璋紒
绛旓細澶у渾鍛ㄩ暱 =3.14脳10=314cm 澶у渾闈㈢Н =3.14脳(10/2)²=78.5cm²灏忓渾鍛ㄩ暱 =2脳3.14脳3=18.84cm 灏忓渾闈㈢Н =3.14脳3²=28.26cm²鍙冲浘鍛ㄩ暱 =2脳3.14脳32+100脳2=501.44m 鍙冲浘闈㈢Н =3.14脳32²+100脳32脳2 =9615.36m²
绛旓細314cm锛堝鍛ㄩ暱锛夐櫎浠3.14锛埾锛夌瓑浜100cm锛堢洿寰勶級100cm锛堢洿寰勶級闄や互2绛変簬50cm锛堝崐寰勶級鎴潰绉=鍗婂緞鐨勫钩鏂逛箻3.14锛埾锛50cm鐨勫钩鏂逛箻3.14=7850骞虫柟鍘樼背锛堟埅闈㈢Н锛夋埅闈㈢Н=7850骞虫柟鍘樼背
绛旓細宸茬煡鍛ㄩ暱鏄314cm 鎴戜滑鍙互鍏堢畻鍑哄渾鏌卞舰鐨勫崐寰 鏍规嵁鍦嗗舰鍛ㄩ暱璁＄畻鍏紡 鍛ㄩ暱=蟺 x d 鍗筹細314cm=3.14 X d 鍒欑洿寰 d =100cm 鍗婂緞r鍒欎负: 50cm 鍦嗗舰闈㈢Н璁＄畻鍏紡锛 鍦嗗舰搴曢潰绉=蟺 x r2 鍗筹細 鍦嗗舰搴曢潰绉=3.14 x (50cm x 50cm) = 7850骞虫柟鍘樼背 瑕佺畻鍑轰綋绉殑璇濆氨瑕佸啀涔樹笂楂樺害 鍗筹細7850...
绛旓細1.鍛ㄩ暱锛3.14*8=25.12鍒嗙背锛岄潰绉锛3.14*(8/2)^2=50.24骞虫柟鍒嗙背 2.闀垮害 3.鍛ㄩ暱涓12.56绫筹紝鎵浠鍦嗛潰绉锛3.14*锛12.56/3.14/2)^2=12.56骞虫柟绫 姝ｆ柟褰㈤潰绉細锛12.56/4)^2=9.8596骞虫柟绫 鏁咃細鍦嗛潰绉ぇ 4.鍛ㄩ暱澶э細3.14*10*2-3.14*8=37.68鍘樼背 闈㈢Н澶э細3.14*10^2-3....
绛旓細2 314/(2*3.14)=50cm 3 鐢蹭箼涓鍦嗗懆闀涔嬫瘮灏辨槸鍗婂緞涔嬫瘮 =31.2锛62.4=1锛2 鏁呯敳鍦嗗懆闀垮氨鏄箼鍦嗙殑浜屽垎涔嬩竴 4 鍦嗗績瑙=寮ч暱闄や互鍗婂緞 6/15*360=144搴 5 S=蟺*r^2=蟺*(C/2蟺)^2=C^2/4蟺=12.56骞虫柟绫 6 閽堝皷灏辨槸鎵簡3/4鐨勫渾 3/4*2*蟺*1.2=5.652鍒嗙背 浠ヤ笂璁＄畻鍧...
