人教版九年级数学上册期末考试卷带答案【必考】 下载本文

右转 直行 (左转,右转) (左转,直行) (右转,右转) (右转,直行) (直行,右转) (直行,直行) (2)(3分)由上表知:两辆汽车都向左转的概率是:

1. 922.(本小题满分8分)

解:解法一,选用①②④,...............................................................................3分

∵AB⊥FC,CD⊥FC, ∴∠ABF=∠DCE=90°,..................................................................................4分 又∵AF∥DE,

∴∠AFB=∠DEC,.........................................................................................5分 ∴△ABF∽△DCE,........................................................................................6分 ∴

ABFB,...............................................................................................7分 ?DCCE又∵DC=1.5m,FB=7.6m,EC=1.7m, ∴AB=6.7m.

即旗杆高度是6.7m.......................................................................................8分 解法二,选①③⑤.............................................................................................3分 过点D作DG⊥AB于点G. ∵AB⊥FC,DC⊥FC,

∴四边形BCDG是矩形,................................................................................4分 ∴CD=BG=1.5m,DG=BC=9m,.....................................................................5分 在直角△AGD中,∠ADG=30°,

AG,................................................................................................6分 DG∴AG=33,.....................................................................................................7分

∴tan30°=又∵AB=AG+GB,

∴AB=33?1.5≈6.7m.

即旗杆高度是6.7m..........................................................................................8分 23.(本小题满分9分)

解:(1)(4分)由题意的点A的坐标是(1,3),....................2分

把A(1,3)代入y=

k, x3;.......................................4分 x得k=1×3=3,.............................................................. ...3分 ∴反比例函数的解析式为y=

(2)(5分)点B在此反比例函数的图象上...............................1分

理由如下:过点B作x轴的垂线交x轴于点D, ∵线段OA绕O点顺时针旋转30°得到线段OB, ∴∠AOB=30°,OB=OA=2,∴∠BOD=30°,.......................2分

在Rt△BOD中,BD=

1OB=1,OD=3BD=3,............3分 2∴B点坐标为(3,1),.....................................................4分 ∵当x=3时,y=

3=1, x3的图象上..................5分 x∴点B(3,1)在反比例函数y=

24.(本小题满分8分) 解:由已知有:∠BAE=22°,∠ABC=90°,∠CED=∠AEC=90°

∴∠BCE=158°,∴∠DCE=22°,...............................................................2分 又∵tan∠BAE=

BD, ABCE,..........................................................5分 CD∴BD=AB?tan∠BAE,...............................................................................4分 又∵cos∠BAE=cos∠DCE=

∴CE=CD?cos∠BAE

=(BD-BC)?cos∠BAE.................................................................6分 =( AB?tan∠BAE-BC)?cos∠BAE...............................................7分 =(10×0.4040-0.5)×0.9272

≈3.28(m)...................................................................................8分

25.(本小题满分11分)

(1)(7分)证明:∵AB=AC,∴∠ABC=∠C, ∵∠C=∠D,∴∠ABC=∠D, 又∵∠BAE=∠EAB, ∴△ABE∽△ADB,...........................................................2分 ∴ABAE, ?ADAB∴AB2=AD?AE=(AE+ED)?AE=(2+4)×2=12, ∴AB=23.....................................................................3分 ∵BD为⊙O的直径,∴∠BAD=90° ∴tan?ABE??AE23 ??AB233∴?ABE?30..................................................................5分 ∴?ADB?30 ∴?CBD?30,∴AC//BD.......................................6分 ?连接OA,OB,∴OA=23,?AOC?60 ??∴S阴影ABC?S扇形AOC?60???12?2?........................7分 360(2)(4分)直线FA与⊙O相切,.........................................................1分 理由如下: ∵?ABC?30,AB?AC, ∴?C?30,∴?AOB?60, ∴?AOB.是等边三角形..............................................................2分 ∴AB=BO,?BAO??ABO?60, ∴?FAB?????1?ABO?30?,∴∠OAF=90°,........................................3分 2∴直线FA与⊙O相切...............................................................................4分 26.(本小题满分12分) 解:(1)(6分)由已知,得B(3,0),C(0,3),..............2分 ∴??3?c,..................................................................4分 0?9?3b?c??b??4解得?,..........................................................................5分 c?3?∴抛物线解析式为y=x2-4x+3;....................................................6分 (2)由(1),得A(1,0),连接BP,................................1分 ∵∠CBA=∠ABP=45°, ∴当BQBC时,△ABC∽△PBQ, ?BPBA∴BQ=3,∴Q1(0,0),.........................................................3分 BQBA时,△ABC∽△QBP, ?BPBC27∴BQ=,∴Q2(,0);..................................................5分 337∴Q点的坐标是(0,0)或(,0)...............................6分 3∴当