
選擇題(本大題共10小題,每小題3分,共30分,在每小題給出的四個選項中,只有一項是符合題目要求的)
二、填空題(本大題共6小題,每小題3分,共18分)
11.32+112.213.8個14.-6
15.5616.15
三、解答題(本大題共7小題,滿分52分.解答應(yīng)寫出文字說明,證明過程或演算步驟)
17.(5分)
【解答】解:原方程可化為x2+2x﹣8=0,·················································(1分)
(x+4)(x﹣2)=0,························································(2分)
x+4=0或x﹣2=0,························································(3分)
∴x1=﹣4,x2=2.······················································(5分)
18.(5分)
【解答】解:原式=2×12+2×12+3×1······························(3分)
=1+1+3························································(3分)
=5.························································(5分)
19.(6分)
【解答】解:(1)如圖,△A1B1C1為所作;········································(2分)
(2)如圖,△A2B2C2為所作;
·····························(4分)
(3)△A2B2C2三個頂點的坐標(biāo)分別為A2(6,0),B2(6,4),C2(2,6).·············(6分)
20.(7分)
【解答】解:(1)由題意可得:點B(3,﹣2)在反比例函數(shù)y2=mx圖象上,
∴-2=m3,則m=﹣6,
∴y2=-6x,
將A(﹣1,n)代入y2=-6x,·························(2分)
得:n=-6-1=6,即A(﹣1,6),
將A,B坐標(biāo)代入一次函數(shù)解析式中,得:
-2=3k+b6=-k+b,解得:k=-2b=4,
∴一次函數(shù)解析式為y1=﹣2x+4;·························(4分)
(2)設(shè)點P的坐標(biāo)為(a,0)(a<0),
∵一次函數(shù)解析式為y1=﹣2x+4,令y=0,則x=2,
∴直線AB與x軸交于點(2,0),
由△ABP的面積為16,可得:12×8×|a-2|=16,·························(6分)
解得:a=﹣2或a=6(舍去),
∴P(﹣2,0).·························(7分)
21.(7分)
【解答】解:延長AD交EF于點G,設(shè)EG=x,
由題意可知:AG⊥EF,
∴∠B=∠F=∠AGF=90°,
∴四邊形ABFG是矩形,···················(1分)
∵∠EAG=45°,
∴∠AEG=90°﹣∠EAG=45°,
∴AG=EG=x,
∵AD=7,
∴DG=x﹣7,
∵∠EDG=60°,
∴tan∠EDG=EGDG=3,·······················(3分)
∴xx-7=3,
∴x=7(3+3)2,························(5分)
∴EG=7(3+3)2,
∵GF=AB=1.68,
∴EF=EG+GF
=7(3+3)2+1.68 ······························(6分)
≈7(3+1.732)2+1.68
=16.562+1.68
=18.242
≈18.2.
故旗桿高度約18.2m.······························(7分)
22.(10分)
【解答】解:(1)設(shè)該品牌頭盔銷售量的月增長率為x,·································(1分)
依題意,得:150(1+x)2=216,···············································(3分)
解得:x1=0.2=20%,x2=﹣2.2(不合題意,舍去).······························(5分)
答:該品牌頭盔銷售量的月增長率為20%.
(2)設(shè)該品牌頭盔的實際售價為y元,
依題意,得:(y﹣30)[600﹣10(y﹣40)]=10000,·····························(7分)
整理,得:y2﹣130y+4000=0,
解得:y1=80(不合題意,舍去),y2=50,·········································(9分)
答:該品牌頭盔的實際售價應(yīng)定為50元.······································(10分)
23.(12分)
【解答】(1)證明:如圖1,過點D作DF⊥BC,交AB于點F,
則∠BDE+∠FDE=90°,··································(1分)
∵DE⊥AD,
∴∠FDE+∠ADF=90°,
∴∠BDE=∠ADF,
∵∠BAC=90°,∠ABC=45°,
∴∠C=45°,
∵M(jìn)N∥AC,
∴∠EBD=180°﹣∠C=135°,
∵∠BFD=45°,DF⊥BC,
∴∠BFD=45°,BD=DF,
∴∠AFD=135°,
∴∠EBD=∠AFD,······················································(2分)
在△BDE和△FDA中
∠EBD=∠AFDBD=DF∠BDE=∠ADF,
∴△BDE≌△FDA(ASA),
∴AD=DE;································································(3分)
(2)解:∴DE=3AD;·················································(4分)
理由:如圖2,過點D作DG⊥BC,交AB于點G,
則∠BDE+∠GDE=90°,
∵DE⊥AD,
∴∠GDE+∠ADG=90°,
∴∠BDE=∠ADG,
∵∠BAC=90°,∠ABC=30°,
∴∠C=60°,
∵M(jìn)N∥AC,
∴∠EBD=180°﹣∠C=120°,
∵∠ABC=30°,DG⊥BC,
∴∠BGD=60°,
∴∠AGD=120°,
∴∠EBD=∠AGD,
∴△BDE∽△GDA,································································(6分)
∴ADDE=DGBD,
在Rt△BDG中,
DGBD=tan30°=33,
∴DE=3AD;································································(7分)
(3)AD=DE?tanα;···························································(8分)
理由:如圖2,∠BDE+∠GDE=90°,
∵DE⊥AD,
∴∠GDE+∠ADG=90°,
∴∠BDE=∠ADG,
∵∠EBD=90°+α,∠AGD=90°+α,
∴∠EBD=∠AGD,
∴△EBD∽△AGD,····························································(10分)
∴ADDE=DGBD,
在Rt△BDG中,
DGBD=tanα,則ADDE=tanα,
∴AD=DE?tanα.····························································(12分)
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