请问？圆的面积怎么算？ 如果知道了圆的直径.要怎么求圆的面积?
\u5706\u7684\u9762\u79ef\u600e\u4e48\u7b97\uff1f\u4e3a\u4ec0\u4e48?d=2\u221a\uff08s/\u03c0\uff09\u3002s\u4e3a\u5706\u7684\u9762\u79ef\uff0c\u03c0\u4e3a\u5706\u5468\u7387\u3002
\u5206\u6790\u8fc7\u7a0b\u5982\u4e0b\uff1a
\u5047\u8bbe\u5706\u7684\u9762\u79ef\u4e3as\uff0c\u6839\u636e\u5706\u7684\u9762\u79ef\u516c\u5f0f\u53ef\u5f97\uff1as=\u03c0r²\u3002
\u5f97\u5230r=\u221a\uff08s/\u03c0\uff09\u3002
\u518d\u6839\u636e\u76f4\u5f84\u662f\u534a\u5f84\u7684\u4e24\u500d\u53ef\u5f97\uff1ad=2r=2\u221a\uff08s/\u03c0\uff09\u3002
\u6269\u5c55\u8d44\u6599\uff1a
\u4e0e\u5706\u76f8\u5173\u7684\u516c\u5f0f\uff1a
1\u3001\u5706\u9762\u79ef\uff1aS=\u03c0r²\uff0cS=\u03c0(d/2)²\u3002\uff08d\u4e3a\u76f4\u5f84\uff0cr\u4e3a\u534a\u5f84\uff09\u3002
2\u3001\u534a\u5706\u7684\u9762\u79ef\uff1aS\u534a\u5706=(\u03c0r^2)/2\u3002\uff08r\u4e3a\u534a\u5f84\uff09\u3002
3\u3001\u5706\u73af\u9762\u79ef\uff1aS\u5927\u5706-S\u5c0f\u5706=\u03c0(R^2-r^2)(R\u4e3a\u5927\u5706\u534a\u5f84\uff0cr\u4e3a\u5c0f\u5706\u534a\u5f84)\u3002
4\u3001\u5706\u7684\u5468\u957f\uff1aC=2\u03c0r\u6216c=\u03c0d\u3002\uff08d\u4e3a\u76f4\u5f84\uff0cr\u4e3a\u534a\u5f84\uff09\u3002
5\u3001\u534a\u5706\u7684\u5468\u957f\uff1ad+(\u03c0d)/2\u6216\u8005d+\u03c0r\u3002\uff08d\u4e3a\u76f4\u5f84\uff0cr\u4e3a\u534a\u5f84\uff09\u3002
绛旓細2銆佹鏂瑰舰鐨勫懆闀=杈归暱脳4 C=4a銆3銆侀暱鏂瑰舰鐨勯潰绉=闀棵楀 S=ab銆4銆佹鏂瑰舰鐨勯潰绉=杈归暱脳杈归暱 S=a^2銆5銆佷笁瑙掑舰鐨勯潰绉=搴暶楅珮梅2 S=ah梅2銆6銆佸钩琛屽洓杈瑰舰鐨勯潰绉=搴暶楅珮 S=ah銆7銆佹褰㈢殑闈㈢Н=锛堜笂搴+涓嬪簳锛壝楅珮梅2 S=锛坅锛媌锛塰梅2銆8銆鍦嗙殑闈㈢Н=鍦嗗懆鐜嚸楀崐寰劽楀崐寰=蟺r^2銆9...
绛旓細鍦嗙殑闈㈢Н锛歋=蟺r²=蟺d²/4 鎵囧舰寮ч暱锛歀=鍦嗗績瑙掞紙寮у害鍒讹級 * r = n掳蟺r/180掳锛坣涓哄渾蹇冭锛夋墖褰㈤潰绉細S=n蟺 r²/360=Lr/2锛圠涓烘墖褰㈢殑寮ч暱锛夊渾鐨勭洿寰勶細 d=2r 鍦嗛敟渚ч潰绉細 S=蟺rl锛坙涓烘瘝绾块暱锛夊渾閿ュ簳闈㈠崐寰勶細 r=n掳/360掳L锛圠涓烘瘝绾块暱锛夛紙r涓哄簳闈㈠崐寰勶級1銆...
绛旓細鍦嗛潰绉锛歋=蟺r²锛孲=蟺(d/2)²銆傦紙d涓虹洿寰勶紝r涓哄崐寰勶紝蟺鏄渾鍛ㄧ巼锛岄氬父鍙3.14锛夈傚湪涓涓钩闈㈠唴锛屼竴鍔ㄧ偣浠ヤ竴瀹氱偣涓轰腑蹇冿紝浠ヤ竴瀹氶暱搴︿负璺濈鏃嬭浆涓鍛ㄦ墍褰㈡垚鐨勫皝闂洸绾垮彨鍋氬渾銆傚渾鏈夋棤鏁颁釜鐐广傚湪鍚屼竴骞抽潰鍐咃紝鍒板畾鐐圭殑璺濈绛変簬瀹氶暱鐨勭偣鐨勯泦鍚堝彨鍋氬渾銆傚渾鍙互琛ㄧず涓洪泦鍚坽M||MO|=r},鍦...
绛旓細鍦嗛潰绉鏄寚鍦嗗舰鎵鍗犵殑骞抽潰绌洪棿澶у皬锛屽父鐢⊿琛ㄧず锛鍦嗙殑闈㈢Н鍏紡涓猴細S=蟺r²銆傚叾涓璖琛ㄧず鍦嗙殑闈㈢Н锛浵涓哄渾鍛ㄧ巼锛屽畠鏄竴涓棤闄愪笉寰幆灏忔暟锛屼竴鑸棤鐗规畩瑕佹眰鐨勬儏鍐典笅锛璁＄畻涓鈮3.14锛況鏄渾鐨勫崐寰勩傚渾鏄竴绉嶈鍒欑殑骞抽潰鍑犱綍鍥惧舰锛屽叾璁＄畻鏂规硶鏈夊緢澶氱锛屾瘮杈冨父瑙佺殑鏄紑鏅嫆鐨勬眰瑙ｆ柟娉曪紝鍗＄摝鍒╅噷鐨勬眰瑙...
绛旓細鍦嗙殑闈㈢Н鍏紡鏄渾鍛ㄧ巼涔樹互鍗婂緞鐨勫钩鏂癸紝鑰屽崐寰勬槸鐩村緞鐨勪竴鍗婏紝绠鑰岃█涔嬶紝灏辨槸鐩村緞涔樹互鍦嗗懆鐜囧啀闄や互2銆傝鍦嗗崐寰勪负r锛岄潰绉负S锛屽垯闈㈢НS=蟺路r2锛埾 琛ㄧず鍦嗗懆鐜囷級銆傚嵆鍦嗛潰绉绛変簬鍦嗗懆鐜囦箻浠ュ渾鍗婂緞鐨勫钩鏂广
绛旓細S=蟺r?鎴朣=蟺*锛坉/2)?銆俽锛氬渾鐨勫崐寰勩俤锛氬渾鐨勭洿寰勩傁锛氬渾鍛ㄧ巼锛屾槸鏃犻檺涓嶅惊鐜皬鏁帮紝涓鑸彇鍊3.14銆傜害缈板凹鏂峰紑鏅嫆杩愮敤鏃犵┓鍒嗗壊娉曪紝姹傚嚭浜嗚澶氬浘褰鐨勯潰绉銆1615骞达紝浠栧皢鑷繁鍒涢犵殑杩欑姹鍦嗛潰绉鐨勬柊鏂规硶锛屽彂琛ㄥ湪銆婅憽钀勯厭妗剁殑绔嬩綋鍑犱綍銆嬩竴涔︿腑銆備粬鎶婂渾鍒嗗壊鎴愭棤绌峰涓皬鎵囧舰锛屽苟鏋滄暍鍦版柇瑷锛氭棤绌...
绛旓細鍦嗛潰绉绠鍏紡鏄細S=蟺r²鎴朣=蟺*锛坉/2)²銆傛妸鍦嗗钩鍧囧垎鎴愯嫢骞蹭唤锛屽彲浠ユ嫾鎴愪竴涓繎浼肩殑闀挎柟褰傞暱鏂瑰舰鐨勫灏辩瓑浜庡渾鐨勫崐寰勶紙r锛夛紝闀挎柟褰㈢殑闀垮氨鏄渾鍛ㄩ暱锛圕锛夌殑涓鍗娿傞暱鏂瑰舰鐨勯潰绉槸ab锛岄偅鍦嗙殑闈㈢Н灏辨槸锛氬渾鐨勫崐寰勶紙r锛変箻浠ヤ簩鍒嗕箣涓鍛ㄩ暱C锛孲=r*C/2=r*蟺r锛屾湁鍏崇殑鍏紡杩樻湁锛1銆...
绛旓細鍦嗛潰绉鍏紡鏄渾鍛ㄧ巼*鍗婂緞鐨勫钩鏂癸紝鐢ㄥ瓧姣嶅彲浠ヨ〃绀轰负锛歋=蟺r²鎴朣=蟺*锛坉/2)²銆傦紙蟺琛ㄧず鍦嗗懆鐜囷紝r琛ㄧず鍗婂緞锛宒琛ㄧず鐩村緞锛夈
绛旓細14涔樹互2鐨勫钩鏂癸紝缁璁＄畻锛岃鍦嗙殑闈㈢Н涓12.56骞虫柟鍘樼背銆傚紑鏅嫆涔熶豢鐓у垏瑗跨摐鐨勬柟娉曪紝鎶婂渾鍒嗗壊鎴愯澶氬皬鎵囧舰锛涗笉鍚岀殑鏄紝浠栦竴寮濮嬪氨鎶婂渾鍒嗘垚鏃犵┓澶氫釜灏忔墖褰鍦嗛潰绉绛変簬鏃犵┓澶氫釜灏忔墖褰㈤潰绉殑鍜岋紝鎵浠ュ湪鏈鍚庝竴涓紡瀛愪腑锛屽悇娈靛皬寮х浉鍔犲氨鏄渾鐨勫懆闀2蟺r锛岃繖灏辨槸鎴戜滑鎵鐔熸倝鐨勫渾鍛ㄩ暱鍏紡銆
绛旓細涓銆佸懆闀垮叕寮 1銆佸渾鐨勫懆闀 锛欳=2蟺r 锛坮锛氬崐寰勶級2銆佸崐鍦嗗懆闀匡細C=蟺r+2r 浜屻鍦嗙殑闈㈢Н 1銆侀潰绉細S=蟺r²2銆佸崐鍦嗛潰绉細S=蟺r²/2 涓夈佸姬闀胯搴﹀叕寮 1銆佹墖褰㈠姬闀匡細L=鍦嗗績瑙掞紙寮у害鍒讹級脳R= n蟺R/180锛埼镐负鍦嗗績瑙掞級锛圧涓烘墖褰㈠崐寰勶級2銆佹墖褰㈤潰绉細S=n蟺 R²/360=LR/...
