求圆心角为120度，半径为3厘米的扇形的周长 已知扇形的圆心角为120°，半径为3，扇形的周长为 ...
\u5df2\u77e5\u6247\u5f62\u7684\u5706\u5fc3\u89d2\u4e3a120\u5ea6\uff0c\u534a\u5f84\u4e3a3\uff0c\u6247\u5f62\u7684\u5468\u957f\u529b\u591a\u5c11\u5f27\u957f
3\u00d72\u00d73.14\u00d7\uff08120\u00f7360\uff09=6.28
\u6247\u5f62\u5468\u957f
6.28+3\u00d72=12.28
6+2\u03c0\uff0e \u8bd5\u9898\u5206\u6790\uff1a\u76f4\u63a5\u5229\u7528\u5f27\u957f\u516c\u5f0f\u6c42\u51fa\u6247\u5f62\u5f27\u957f\uff0c\u8fdb\u800c\u5f97\u51fa\u6247\u5f62\u7684\u5468\u957f\uff0e\u2235\u6247\u5f62\u7684\u5706\u5fc3\u89d2\u4e3a120\u00b0\uff0c\u534a\u5f84\u4e3a3\uff0c\u2234\u6247\u5f62\u7684\u5f27\u957f\u4e3a\uff1a \uff0c\u2234\u6247\u5f62\u7684\u5468\u957f\u4e3a\uff1a6+2\u03c0\uff0e\u8003\u70b9: \u5f27\u957f\u7684\u8ba1\u7b97\uff0e
弧长=180分之120X3Xπ=2π
周长=2π+3+3
=12.28（cm）
弧长=120÷360×2×3×π=2π，周长=弧长+2半径=2π+2×3=2π+6
3分之1乘2乘3.14乘3
绛旓細鎵囧舰闈㈢НS =[锛鍦嗗績瑙鐨勫害鏁帮級梅锛360锛塢脳3.14*R鐨勫钩鏂 =(120梅360锛壝3.14脳3脳3 =9.42(骞虫柟鍘樼背)
绛旓細寮ч暱=180鍒嗕箣120X3X蟺 =2蟺 鍛ㄩ暱=2蟺+3+3 =12.28锛坈m锛
绛旓細宸茬煡鎵囧舰鐨鍗婂緞涓R=3cm锛鍦嗗績瑙掍负A=120搴︼紝鎵囧舰鐨勯潰绉负Scm骞虫柟锛堢粨鏋滀繚鐣檖ai)S=PI*R^2*A/360 =PI*3^2*120/360 =PI*9/3 =3*PI骞虫柟鍘樼背
绛旓細3 2015-02-04 鑻ョ敤鍗婂緞涓9,鍦嗗績瑙掍负120掳鐨勬墖褰㈠洿鎴愪竴涓渾閿ョ殑渚ч潰(鎺ョ紳... 2015-02-08 鐢ㄥ崐寰勪负30cm,鍦嗗績瑙掍负120掳鐨勬墖褰㈠洿鎴愪竴涓渾閿ョ殑渚ч潰,... 2014-03-09 鐢ㄤ竴涓崐寰勪负9cm,鍦嗗績瑙掍负120º鐨勬墖褰㈠洿鎴愪竴涓... 2013-09-13 鐢ㄤ竴涓鍦嗗績瑙掍负120搴,鍗婂緞涓鍥涚殑鎵囧舰鍋氫竴涓渾閿ョ殑渚ч潰,杩欎釜... 5...
绛旓細鍦ㄤ竴涓鍗婂緞涓3cm鐨勫渾涓,鐢讳竴涓鍦嗗績瑙掍负120搴鐨勬墖褰,杩欎釜鎵囧舰鐨勯潰绉=1/3脳鍦嗙殑闈㈢Н =1/3脳3.14脳3脳3 =9.42骞虫柟鍘樼背锛
绛旓細宸茬煡鎵囧舰鐨鍦嗗績瑙掍负A=120搴︼紝鍗婂緞涓R=3cm鍒欒鎵囧舰鐨勯潰绉疭锛(缁撴灉淇濈暀蟺锛 璇ユ墖褰㈢殑闈㈢НS=蟺*R^2*A/360=蟺*3^2*120/360=3*蟺骞虫柟鍘樼背
绛旓細鍗婂緞涓3鐨勫渾鍏跺懆闀匡紳3*2*3.14锛120搴鐨鍦嗗績瑙鎵瀵圭殑寮ч暱涓哄渾鍛ㄩ暱鐨1/3,鎵浠ユ槸2*3.14锛岃繖灏辨槸鍦嗛敟搴曢潰鐨勫懆闀匡紝鎵浠ュ叾搴曢潰鍗婂緞锛2*3.14/2/3.14=1
绛旓細S=120/360*蟺*3²=3蟺=9.42
绛旓細120搴鎵囧舰,涔熷氨鏄1/3涓渾,蟺*r^2=9蟺,鎵浠ユ墖褰㈤潰绉鏄3蟺骞虫柟鍘樼背
绛旓細S=蟺r^2/3 鏄鍗婂緞涓3鐨勫渾闈㈢Н鐨1/3銆1/3鏄120/360绠楀嚭鏉ョ殑銆
