-初三几何数学题,高手帮忙啊!!!!!!
\u521d\u4e09\u51e0\u4f55\u6570\u5b66\u9898\u5206\u6790:
\u8fd9\u4e2a\u9898\uff0c\u5176\u5b9e\u4e0d\u7b97\u96be\u9898\u5427\uff0c\u53ea\u662f\u6709\u4e00\u4e2a\u6761\u4ef6\u662f\u8ff7\u60d1\u4eba\u7684:"\u2220EAB=\u03b1"
\u5b9e\u9645\u4e0a\u8fd9\u8fd9\u9898\u4e0e\u8fd9\u4e2a\u65e0\u5173\uff0c\u771f\u6b63\u6709\u7528\u7684\u662f "\u2220CEF=90\u00b0"\u4e5f\u5c31\u662f\u5782\u76f4\u5173\u7cfb
\u5982\u56fe\uff0c\u770b\u5230\u8fd9\u6837\u7684\u4e09\u89d2\u5f62\uff0c\u5269\u4e0b\u7684\u4e1c\u897f\u52fe\u80a1\u5b9a\u7406\u5c31\u80fd\u89e3\u51b3\u4e86~
\uff08\u6ce8\uff1a 5/2\uff1a\u8868\u793a2\u5206\u4e4b\u4e94; \u221a3:\u8868\u793a\u6839\u53f73\uff09
\u89e3\uff1a
\u8fde\u63a5AC\uff0c\u5ef7\u957fCE\u4ea4AG\u4e8eH\u70b9
\u2235\u2220CEF=90\u00b0,\u53c8AG\u2225EF
\u2234\u2220EHG=90\u00b0\uff0c\u5373\u2220CHA=90\u00b0
Rt\u25b3AEH\u4e2d\u2220HAE=60\u00b0\uff0cAE=5
\u2234AH=5/2 HE=(5/2)\u221a3
AC\u4e3a\u83f1\u5f62\u5bf9\u89d2\u7ebf\uff0c\u5bb9\u6613\u7b97\u51faAC=5\u221a3 (\u8fd9\u4e2a\u7684\u786e\u5bb9\u6613\uff0c\u4f60\u81ea\u5df1\u6765\uff09
Rt\u25b3ACH\u4e2d,\u8bbeCE=x\u7531\u52fe\u80a1\u5b9a\u7406
AH² +HC² =AC²
(5/2)² +[(5/2)\u221a3+x]²=(5\u221a3)²
\u5316\u7b80\u5f97x²-(5\u221a3)x-50=0
\u7528\u6c42\u6839\u516c\u5f0f\u6c42\u5f97
x=(-5\u221a3\u00b1\u221a275)/2
\u5316\u7b80\uff0c\u820d\u53bb\u8d1f\u6839\u5f97\u5230
x=5(\u221a11-\u221a3)/2
\u2234S\u25b3CEF=½CE\u00d7EF=½\u00d75(\u221a11-\u221a3)/2\u00d75=(25/4)\u00d7(\u221a11-\u221a3)
\u662f\u5728\u4e00\u7ebf\u7684\u3002\u9996\u5148\u4f60\u5f97\u77e5\u9053\u89d2\u5e73\u5206\u7ebf\u4e0a\u7684\u70b9\u7684\u7279\u5f81\uff1a\u89d2\u5e73\u5206\u7ebf\u4e0a\u7684\u70b9\u5230\u89d2\u4e24\u8fb9\u7684\u8ddd\u79bb\u76f8\u7b49\u3002\u53ef\u77e5M\u5230AB\u548cBC\u7684\u8ddd\u79bb\u76f8\u7b49\uff0c\u540c\u7406M\u5230AC\u548cBC\u7684\u8ddd\u79bb\u76f8\u7b49\uff0c\u4ee5M\u5230BC\u7684\u8ddd\u79bb\u4e3a\u6865\u6881\u53ef\u77e5M\u5230AB\u548cAC\u7684\u8ddd\u79bb\u76f8\u7b49\uff0c\u5373M\u5728\u89d2A\u7684\u89d2\u5e73\u5206\u7ebf\u4e0a\u3002\u540c\u7406N\u5230BE\u548cED\u7684\u8ddd\u79bb\u76f8\u7b49\uff0cN\u5230ED\u548cDC\u7684\u8ddd\u79bb\u76f8\u7b49\uff0c\u4ee5ED\u4e3a\u6865\u6881\u53ef\u77e5N\u5230AB\u548cAC\u8ddd\u79bb\u76f8\u7b49\uff0c\u5373N\u5728\u89d2A\u7684\u89d2\u5e73\u5206\u7ebf\u4e0a\uff0c\u6545\u4e09\u70b9\u4e00\u76f4\u7ebf\u3002
\u63d0\u793a\uff1a\u4e3b\u8981\u5229\u7528\u89d2\u5e73\u5206\u7ebf\u4e0a\u7684\u70b9\u5230\u89d2\u4e24\u8fb9\u7684\u8ddd\u79bb\u76f8\u7b49\u548c\u5230\u89d2\u4e24\u8fb9\u7684\u8ddd\u79bb\u76f8\u7b49\u7684\u70b9\u5728\u89d2\u5e73\u5206\u7ebf\u4e0a\u8fd9\u4e24\u70b9\u3002
\u8fd8\u662f\u4e0d\u660e\u767d\u53ef\u4ee5\u95ee\u6211
若AD=10,也不能出现。
(2)利用三角形相似知识。直角三角形PDQ,ECQ,BAP相似,可以根据CE=2cm求数量关系。直角三角板只有两种规格,即等腰直角三角形,和30度直角三角形。可以分两种情况讨论。
1. ∵角HPF是直角,所以△ABP∽△PDF ∴AP/AB=CD/PD=CD/(AD-AP) 求得AP=2或8
2. CE=2那么BE=8,作EF垂直AD交AD于F点,△ABP∽△PEF,AP/AB=EF/(AF-AP)
求得AP=4
若是45度的三角板,使HF与BC保持平行,根据相似三角形及对称,易得第一问AP=5cm,第二问AP=4cm.全是手机打的..
不能
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绛旓細璇佹槑锛氳繃A浣淎G鈯C浜嶨锛屼氦CD浜嶩 鈭典笁瑙掑舰ABC鏄瓑鑵扮洿瑙掍笁瑙掑舰 鈭粹垹CAG=鈭燘锛孉C=AB 鈭碘垹ACD+鈭燙DA=鈭燚AF+鈭燙DA=90掳 鈭粹垹CAD=鈭燚CF 鈭粹柍ACH鈮屸柍ABF 鈭碅H=BF 鍦ㄢ柍ADH鍜屸柍BDF涓 BD=AD锛屸垹BAG=鈭燘=45掳锛孉H=BF 鈭粹柍ADH鈮屸柍BDF 鈭粹垹ADC=鈭燘DF ...
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绛旓細1 AD OC浜ょ偣涓篍 瑙扐DC=AOB 瑙扐EO=DEC寰楄OAD=OCD 鎵浠ヤ笁瑙掑舰AOE鈭紻EC 寰桝E:EC=OE:ED 鎺ㄥ嚭AE:OE=EC:ED 瑙扥ED=AEC鎵浠ヤ笁瑙掑舰OED鈭紸EC 鎵浠OE=DAC=45掳鎵浠OD=90掳 (1)杩嘋浣淢C鈯C锛屽啀寤堕暱OA锛屼笌MC浜や笌M鐐 鈭碘柍AOB涓虹瓑鑵癛T鈻 鈭粹垹AOB=45掳 鈭礛C鈯C 鈭粹垹MCO=90掳=鈭燤CA+鈭燗CO...
绛旓細浣淐D鐨勫鸡蹇冭窛OM锛岃繛鎺D銆傜敱宸茬煡寰桝B=2+6=8锛汚O=OD=4锛汷E=4-2=2锛屽湪鐩磋涓夎褰ME涓紝鐢扁垹DEB=30掳锛屽緱OM=OE/2=2脳1/2=1锛屽湪鐩磋涓夎褰MD涓紝MD=鈭(4骞虫柟-1骞虫柟)=鈭15.鐢盋M=MD寰桟D=2MD=2鈭15銆
绛旓細1 AD OC浜ょ偣涓篍 瑙扐DC=AOB 瑙扐EO=DEC寰楄OAD=OCD 鎵浠ヤ笁瑙掑舰AOE鈭紻EC 寰桝E:EC=OE:ED 鎺ㄥ嚭AE:OE=EC:ED 瑙扥ED=AEC鎵浠ヤ笁瑙掑舰OED鈭紸EC 鎵浠OE=DAC=45掳鎵浠OD=90掳 (1) 杩嘋浣淢C鈯C锛屽啀寤堕暱OA锛屼笌MC浜や笌M鐐 鈭碘柍AOB涓虹瓑鑵癛T鈻 鈭粹垹AOB=45掳 鈭礛C鈯C 鈭粹垹MCO=90掳=鈭燤CA+鈭...
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