如下图，正方形BEFG边长为7米，正方形ABCD的边长为5米，求阴影部分的面积。 如下图，正方形BEFG的边长为7米，正方形ABCD的边长为5...
\u4e0b\u56fe\u6b63\u65b9\u5f62BEFG\u7684\u8fb9\u957f\u4e3a7\u7c73\uff0c\u6b63\u65b9\u5f62ABCD\u7684\u8fb9\u957f\u4e3a5\u7c73\uff0c\u6c42\u5b66\u9738\u7b97\u4e0b\u9634\u5f71\u90e8\u5206\u9762\u79ef\uff017\u00d77+5\u00d75-5\u00d75\u00f72-7\u00d7\uff087+5\uff09\u00f72-7\u00d7\uff087-5\uff09\u00f72
\uff1d74-12.5-42-7\uff1d12.5
Sacb\uff1d1/2x5x5=12.5\u5e73\u65b9\u7c73
Sgfc=1/2x7x2=7\u5e73\u65b9\u7c73
Scfeb=7x7-7=42\u5e73\u65b9\u7c73
Safe=1/2x7x12=42\u5e73\u65b9\u7c73
\u6240\u4ee5\u9634\u5f71\u9762\u79ef
42+12.5-42\uff1d12.5\u5e73\u65b9\u7c73
阴影处面积为5*5+7*7-12.5-7-42=12.5
设AF与BC交于点M，CG=7-5=2，∵BM∶EF=AB∶AE，∴BM∶7=5∶12，∴BM=35/12，∴CM=7-2-35/12=25/12
∴⊿ACF=⊿ACM+⊿FCM=1/2×25/12×5+1/2×25/12×7=25/2
绛旓細濡傚浘,姝ｆ柟褰绾哥墖ABCD鍜BEFG鐨勮竟闀鍒嗗埆涓5鍜2,鎸夊鍥炬墍绀虹殑鏂瑰紡鍓笅2涓槾褰遍儴鍒嗙殑鐩磋涓夎褰,骞舵憜鏀炬垚姝ｆ柟褰HFI,鍒欐鏂瑰舰DHFI鐨杈归暱涓()銆... 濡傚浘,姝ｆ柟褰㈢焊鐗嘇BCD鍜孊EFG鐨勮竟闀垮垎鍒负5鍜2,鎸夊鍥炬墍绀虹殑鏂瑰紡鍓笅2涓槾褰遍儴鍒嗙殑鐩磋涓夎褰,骞舵憜鏀炬垚姝ｆ柟褰HFI,鍒欐鏂瑰舰DHFI鐨勮竟闀夸负( )銆 灞曞紑 鎴戞潵...
绛旓細鏈濡傚浘 宸茬煡ABCD鍜befg鏄鏂瑰舰杈归暱鍒嗗埆涓6cm鍜4cm锛屾眰闃村奖閮ㄥ垎鐨勯潰绉6²-4²=36-16=20骞虫柟鍘樼背 銆傚凡鐭BCD鍜be fg鏄鏂瑰舰杈归暱鍒嗗埆涓6cm鍜4cm锛岄槾褰遍儴鍒嗙殑闈㈢Н鏄20骞虫柟鍘樼背銆
绛旓細銆愮瓟妗堛戣В:(1)濡傚浘鈶,璁姝ｆ柟褰EFG鐨勮竟闀夸负x,鍒橞E=FG=BG=x銆傗埖AB=3,BC=6,鈭碅G=AB锕G=3锕銆傗埖GF鈭E,鈭粹柍AGF鈭解柍ABC銆傗埓 ,鍗炽傝В寰:x=2,鍗矪E=2銆(2)瀛樺湪婊¤冻鏉′欢鐨則,鐞嗙敱濡備笅:濡傚浘鈶,杩囩偣D浣淒H鈯C浜嶩,鍒橞H=AD=2,DH=AB=3,鐢遍鎰忓緱:BB鈥=HE=t,HB鈥=|t锕2|,EC=4锕,鈭礒F...
绛旓細濡傚浘锛岃澶ф鏂瑰舰.ABCD鐨勮竟闀夸负acm,鑰姝ｆ柟褰EFG鐨勮竟闀夸负6cm銆傚垯鈻矨ED涓庢褰BAD鐨勯潰绉兘绛変簬(a+6) xa梅2,鑰屼笖閮藉寘鍚褰BAD,鎵浠モ柍HBE涓庘柍HCD闈㈢Н鐩哥瓑銆傜敱姝ゆ帹鍑洪槾褰遍儴鍒嗙殑闈㈢Н涓庘柍BEG鐨勯潰绉浉绛,绛変簬6x6梅2 =18( cm²)
绛旓細姝ｆ柟褰BCD鐨勮竟闀夸负b,姝ｆ柟褰EFG杈归暱涓a,1)鈻矯DE鍜屸柍CDB鏄悓搴曠瓑楂樹笁瑙掑舰.鈻矯DE鐨勯潰绉=鈻矯DE鐨勯潰绉=b^2/2,2).鈻矯DG鐨勯潰绉=(1/2)*b(a-b)=(ab-b^2)/2 3)琛ュ叏闀挎柟褰EFK,鈻矰EG鐨勯潰绉 =闀挎柟褰EFK闈㈢Н-鈻矨DE闈㈢Н-鈻矱FG闈㈢Н-鈻矰GK闈㈢Н =a(a+b)-(1/2)*b(a+b)-a^2/2-(ab...
绛旓細BD^2=a^2+a^2 BD=鏍瑰彿2a 鍚岀悊BF=鏍瑰彿2b 瑙扗BF=45+45=90 S=1/2BD*BF=ab
绛旓細(1)鈭燙BE=鈭燝BA=45掳銆侫B=BC,BG=BE.鎵浠 鈻矪CE鈮 鈻矪AG锛屾墍浠G=CE.(2)鐢憋紙1锛夌煡S 鈻矨GB=y, S 鈻矨GB=1/2*AB*BG*sin鈭燗BG=3鈭2/2x.F鍦ˋB涓婂彇鐐癸紝鎵浠ュ彲浠ョ煡閬撴渶灏忕殑姝ｆ柟褰BGFE鍜屾渶澶х殑锛屽洜涓烘鏂瑰舰瀛樺湪锛屾墍浠涓嶅彲鑳藉湪A鐐广傛墍浠0<x=<3鈭2.(3),璁綛F鐨勪腑鐐逛负O銆傚綋x=2鈭2...
绛旓細闃村奖闈㈢Н=涓や釜姝ｆ柟褰闈㈢Н-涓や釜涓夎褰㈤潰绉 =6脳6+8脳8-1/2脳6脳(6+8)-1/2脳8脳8 =36+64-42-32 =100-74 =26骞虫柟鍘樼背 鎮ㄥソ锛屽緢楂樺叴涓烘偍瑙ｇ瓟锛宻kyhunter002涓烘偍绛旂枒瑙ｆ儜 濡傛灉鏈鏈変粈涔堜笉鏄庣櫧鍙互杩介棶锛屽鏋滄弧鎰忚寰楅噰绾 濡傛灉鏈夊叾浠栭棶棰樿閲囩撼鏈鍚庡彟鍙戠偣鍑诲悜鎴戞眰鍔╋紝绛旈涓嶆槗锛岃璋呰В锛...
绛旓細姝ｆ柟褰EFG鐨勮竟闀挎槸4鍒橞E=1锛屾墍浠E=4,AD=3,RE=1,RF=1鎵浠モ柍DEK鐨勯潰绉负鈻矰GM+鈻矲KE+姊舰GMRN锛堣DE,CB,浜や笌M锛孌K,FE浜や笌N锛岋級绠楁暟鍗冲彲
绛旓細鍚戝唴鍋氫竴涓笌BEFG涓鏍风殑姝ｆ柟褰紝鈻矨IH鍏ㄧ瓑浜庘柍CGF,鍥犳S澶-S灏=37=CDAB-GHIB锛屾墍浠GFC=1/2锛圕DAB-GHIB锛夊嵆=1/2*37=18.5
