张大爷用15.7米长篱笆围一块地，一面靠墙，为怎样形状使地面积最大？最大几平方米
\u5f20\u5927\u7237\u9760\u5899\u7528\u7bf1\u7b06\u56f4\u4e86\u4e00\u5757\u534a\u5706\u5f62\u83dc\u5730\uff0c\u7bf1\u7b06\u957f12.56\u7c73\u3002\u83dc\u5730\u7684\u9762\u79ef\u662f\u591a\u5c11\u5e73\u65b9\u7c73\uff1f\u5148\u6c42\u51fa\u5706\u7684\u5468\u957f\uff0c\u9664\u4ee53.14\u5f97\u51fa\u76f4\u5f84\uff0c\u518d\u9664\u4ee52\u5f97\u51fa\u534a\u5f84\uff0c\u7528\u534a\u5f84\u7684\u5e73\u65b9\u4e58\u4ee53.14\u5f97\u51fa\u4e00\u4e2a\u5706\u7684\u9762\u79ef\uff0c\u6700\u540e\u9664\u4ee52\u5c31\u7b49\u4e8e\u534a\u4e2a\u5706\u7684\u9762\u79ef\uff0c\u5c31\u662f\u83dc\u5730\u7684\u9762\u79ef\uff1a\uff0812.56\u00d72\u00f73.14\u00f72\uff09²\u00d73.14\u00f72=25.12\uff08\u5e73\u65b9\u7c73\uff09
48-15=33m
\u7b97\u51fa\u68af\u5f62\u7684\u5e95\u548c\u9ad8\u7684\u548c
33\u00d715\u00f72
=495\u00f72
=247.5(\u5e73\u65b9\u7c73)
\u7b97\u51fa\u68af\u5f62\u7684\u9762\u79ef
247.5\u00d79.5
=2351.25(\u5343\u514b)
\u7b97\u51fa\u8fd9\u5757\u5730\u4e00\u5171\u53ef\u4ee5\u6536\u767d\u83dc2351.25\u5343\u514b
绛旓細涓闈㈤潬澧鐢15.7绫抽暱绡辩瑔鍥鎴愬崐鍦嗛潰绉渶澶с傚崐鍦嗙殑鍗婂緞15.7梅3.14=5绫炽傛渶澶ч潰绉负5脳5脳3.14脳1/2=39.25骞虫柟绫
绛旓細瑙ｏ細璁鍥鎴愮殑鑿滃洯鐨勯暱涓 x 绫筹紝鍒欏涓 15.7 - x 绫筹紝鎵浠ヨ彍鍥潰绉负 S = x(15.7-x)=-x�0�5+15.7x x鍘讳笉鍚岀殑鍊硷紝鍥存垚鐨勮彍鍥潰绉垯涓嶅悓锛屽埄鐢ㄧ嚎鎬ц鍒掓眰鍑烘渶澶у 鍗15.7>x>0锛寈�0�5-15.7x<0 ...
绛旓細鍒澶х埛鐢15.7绫抽暱鐨 闈犲鍥翠簡涓涓崐鍦嗗舰鐨勫吇楦″満锛岃涓涓渾鐨勫懆闀垮氨鏄15.7*2=31.4绫筹紝鍛ㄩ暱鍏紡鏄:2 鍗婂緞=2*3.14*r=31.4 绠楀嚭鍗婂緞鏄5 鍦嗙殑 鏄細鍗婂緞*鍗婂緞鎵浠ュ彲浠ョ畻鍑洪潰绉槸 3.14*5*5=78.5 鍗 鏄細78.5闄や互2绛変簬39.25骞虫柟绫虫眰閲囩撼锛侊紒锛
绛旓細鎴戝氨鏄寮犲ぇ鐖锛屾垜鍐冲畾涓嶅洿缇婂湀浜
绛旓細鏍规嵁棰樺共鍒嗘瀽鍙緱锛氬鏋滃洿澧欒鍥鎴愪竴涓 1 4 鍦嗗舰鐨勮彍鍥紝濡備笂鍥炬墍绀猴紝鍒欒繖涓渾鐨勫崐寰勬槸锛15.7脳4梅3.14梅2锛=62.8梅3.14梅2锛=10锛堢背锛夛紝鑿滃湴鐨勯潰绉槸锛3.14脳10 2 脳 1 4 锛=314脳 1 4 锛=78.5锛堝钩鏂圭背锛夛紝绛旓細杩欐牱鍥存垚鐨勮彍鍦扮殑闈㈢Н鏄78.5骞虫柟绫...
绛旓細鐭ラ亾鍛ㄩ暱锛岃姹傞潰绉氨瑕佸厛姹傚嚭鍗婂緞锛鐢15.7梅2梅3.14=2.5锛堝帢绫筹級鐒跺悗鍐嶆眰闈㈢Н锛岀敤2.5脳2.5脳3.14=19.625锛堝钩鏂瑰帢绫筹級
绛旓細鍥炵瓟锛氬垬澶х埛鐢15.7绫抽暱鐨绡辩瑔闈犲鍥翠簡涓涓崐鍦嗗舰鐨勫吇楦″満,璁句竴涓渾鐨勫懆闀垮氨鏄15.7*2=31.4绫,鍛ㄩ暱鍏紡鏄:2*鍦嗗懆鐜*鍗婂緞=2*3.14*r=31.4 绠楀嚭鍗婂緞鏄5 鍦嗙殑闈㈢Н鍏紡鏄:鍦嗗懆鐜*鍗婂緞*鍗婂緞鎵浠ュ彲浠ョ畻鍑洪潰绉槸 3.14*5*5=78.5 鍗婂渾闈㈢Н鏄:78.5闄や互2绛変簬39.25骞虫柟绫
绛旓細(15.7/3.14)^2*3.14梅2 =39.25骞虫柟绫
绛旓細15.7脳2梅3.14梅2=5绫 闈㈢Н=5脳5脳3.14脳1/2=39.25骞虫柟绫
绛旓細瑙ｏ細璁惧崐鍦嗙殑鐩村緞鏄痙绫炽3.14d梅2锛媎=15.7 . 1.57d=15.7 . d=10 .3.14*锛10梅2锛²梅2 =3.14*25梅2 =39.25锛堝钩鏂圭背锛夌瓟锛氳繖涓吇楦″満鐨勯潰绉槸39.25骞虫柟绫炽備綘鐨勭瓟妗堟槸瀹屽叏姝ｇ‘鐨勩傚彲鑳芥槸鑰佸笀澶ф剰浜嗐
