一、选择题(本大题共 16 个小题,共 42分.1-10小题各3分,11-16小题各2分.在每小题给出的四个选项中,只有一项是合题目要求的)
-
-
A . 2
B . -2
C . ±2
D . 16
-
3.
若代数式
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
有意义,则
x的取值范围是( )
A . x=-1
B . x=3
C . x≠-1
D . x≠3
-
4.
使二次根式
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmath%3E)
有意义的
x的取值范围是( )
A . x>2
B . x≥2
C . x=2
D . x≠2
-
5.
如图,两个三角形是全等三角形,
x的值是( )
![](//tikupic.21cnjy.com/2023/12/06/6a/c6/6ac6b7b0a00a22d6b1a7498f80841778_125x146.png)
![](//tikupic.21cnjy.com/2023/12/06/39/f3/39f325109446d4bdded0e3f2bd589e63_143x150.png)
A . 30
B . 45
C . 50
D . 85
-
-
7.
a , b是两个连续整数,若
a<
<b , 则
a , b分别是( )
A . 2,3
B . 3,2
C . 3,4
D . 6,8
-
8.
如图,
DE是
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的边
AB的垂直平分线,
D为垂足,
DE交
AC于点
E , 且
AC=8,
BC=5,则
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EE%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的周长是( )
![](//tikupic.21cnjy.com/2023/12/06/ef/8c/ef8c6812687cf59bfc5283859572b3ca_265x138.png)
A . 12
B . 13
C . 14
D . 15
-
9.
如图是作
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的作图痕迹,则此作图的已知条件为( )
![](//tikupic.21cnjy.com/2023/12/06/9d/58/9d582f16077fb49293db509a513ca771_203x112.png)
A . 已知两角及夹边
B . 已知三边
C . 已知两边及夹角
D . 已知两边及一边夹角
-
10.
若分式
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
的值为零,则
x的值是( )
A . 0
B . 1
C . -1
D . ±1
-
11.
如图,
D是
AB上一点,
DF交
AC于点
E ,
DE=
FE ,
FC∥
AB.若
AB=4
, CF=3,则
BD的长是( )
![](//tikupic.21cnjy.com/2023/12/06/87/0d/870d97e139317c205bcd83d97328666e_201x166.png)
A . 0.5
B . 1
C . 1.5
D . 2
-
12.
如图,数轴上表示1,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmtext%3E2%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmath%3E)
的对应点分别为点
A ,
B , 点
B关于点A对折后的点
C , 则点
C所表示的数是( )
![](//tikupic.21cnjy.com/2023/12/06/d3/5f/d35f1666223fb130128eaf110a19d69b_401x86.png)
-
13.
已知
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmath%3E)
, 则代数式
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmrow%3E%3Cmn%3E7%3C%2Fmn%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E4%3C%2Fmn%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmrow%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmrow%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmrow%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3C%2Fmath%3E)
的值是( )
-
14.
如果关于x的分式方程
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmfrac%3E%3Cmrow%3E%3Cmi%3Em%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
有增根,则
m的值为( )
A . -3
B . 3
C . -1
D . -2
-
15.
如图,在
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
中,∠
A=∠
B ,
M ,
N ,
K分别是
PA ,
PB ,
AB上的点,且
AM=BK ,
BN=AK.若∠
MKN=44°,则∠
P的度数为( )
![](//tikupic.21cnjy.com/2023/12/06/4a/2b/4a2b3d3b687fe79b61becf04c804af6a_248x152.png)
A . 98°
B . 96°
C . 94°
D . 92°
-
16.
一批货物要运往某地,有甲、乙、丙三辆卡车可用,已知甲、乙、丙每次运货量不变,且甲、乙两车单独运完这批货物所用次数之比为2:1。若甲、丙两车各运相同次数运完这批货时,甲共运了180吨;若乙、丙两车各运相同次数运完这批货时,乙共运了270吨.则这批货共有( )
A . 360吨
B . 450吨
C . 540吨
D . 630吨
二、填空题(本大题共4 个小题,每空2分,共12分)
-
17.
-
(1)
计算:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmtext%3E1%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmfrac%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmtext%3E1%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%3D%3C%2Fmo%3E%3C%2Fmath%3E)
.
-
(2)
化简:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmfrac%3E%3Cmrow%3E%3Cmtext%3E3%3C%2Fmtext%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmtext%3E7%3C%2Fmtext%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmtext%3E%3D%3C%2Fmtext%3E%3C%2Fmath%3E)
.
-
18.
-
(1)
已知
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Ey%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmath%3E)
, 则
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmi%3Ey%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ey%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
的值是
.
-
(2)
若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E0%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmrow%3E%3Cmo%3E%7C%3C%2Fmo%3E%3Cmrow%3E%3Cmi%3Eb%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E6%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmo%3E%7C%3C%2Fmo%3E%3C%2Fmrow%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E0%3C%2Fmn%3E%3C%2Fmath%3E)
, 则
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi%3Eb%3C%2Fmi%3E%3C%2Fmath%3E)
的平方根是
.
-
19.
如图,
EB交
AC于点
M , 交
FC于点
D ,
AB交
FC于点
N , ∠E=∠
F=90°,∠
B=∠
C,AE=
AF.给出下列结论:①∠1=∠2; ②
BE=
CF;③
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmi%3EN%3C%2Fmi%3E%3Cmo%3E%E2%89%85%3C%2Fmo%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
.其中正确的结论有
.(填序号)
![](//tikupic.21cnjy.com/2023/12/06/ba/44/ba44e15a22eff31d050ffe6d16eaf67b_183x156.png)
-
20.
如图,
AB=5
cm ,
AC=4
cm.∠
CAB=∠
DBA=60°,点
P 在线段
AB 上以1
cm/
s的速度由点
A向点
B运动,同时,点
Q在射线
BD上由点
B向点
D方向运动.它们运动的时间为
t(
s),则点
Q的运动速度为
cm/
s时,在某一时刻,由
A ,
C ,
P三点构成的三角形与由
B ,
P ,
Q三点构成的三角形全等.
![](//tikupic.21cnjy.com/2023/12/06/f3/e3/f3e3e2a2f8c9319a9bc2ed93c03581b9_205x153.png)
三、解答题(本大题共6个小题,共66分.解答应写出文字说明、证明过程或演算步骤)
-
-
-
23.
-
(1)
先化简,再求值:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E%28%3C%2Fmn%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmn%3E%29%3C%2Fmn%3E%3Cmo%3E%E2%8B%85%3C%2Fmo%3E%3Cmn%3E%28%3C%2Fmn%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E%29%3C%2Fmn%3E%3C%2Fmath%3E)
, 其中
-
(2)
先化简,再求值:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E%28%3C%2Fmn%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E%29%3C%2Fmn%3E%3Cmo%3E%C3%B7%3C%2Fmo%3E%3Cmfrac%3E%3Cmrow%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmi%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
, 其中
-
24.
如图,面积为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3Ec%3C%2Fmi%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Em%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
的正方形四个角是面积为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3Ec%3C%2Fmi%3E%3Cmsup%3E%3Cmrow%3E%3Cmi%3Em%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
的小正方形,现将四个角剪掉,制作一个无盖的长方体盒子.
![](//tikupic.21cnjy.com/2023/12/06/01/dc/01dc8d68abee4dbff08aa9cc5f6f43c6_143x143.png)
-
(1)
则原来大正方形的边长为
cm;(保留根号)
四个角的小正方形的边长为cm.(保留根号)
-
(2)
求这个长方体盒子的底面边长和体积分别是多少?并将结果精确到 0.01.
提示:![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%E2%89%88%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E4%3C%2Fmn%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E4%3C%2Fmn%3E%3Cmn%3E++%EF%BC%8C+%3C%2Fmn%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%E2%89%88%3C%2Fmo%3E%3Cmn%3E1%3C%2Fmn%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E7%3C%2Fmn%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E++%EF%BC%8C+%3C%2Fmn%3E%3Cmsqrt%3E%3Cmrow%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsqrt%3E%3Cmo%3E%E2%89%88%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E.%3C%2Fmn%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmn%3E3%3C%2Fmn%3E%3Cmn%3E6%3C%2Fmn%3E%3C%2Fmath%3E)
-
25.
一辆汽车开往距离出发地 180 km 的目的地,出发后第1小时内按原计划的速度匀速行驶,1小时后按原来速度的1.5倍匀速行驶,结果比原计划提前40min 到达目的地.
-
-
(2)
汽车出发时油箱有7.5升油,到达目的地时还剩4.3升油,若汽车提速后每小时的耗油量比原速每小时的耗油量多0.3升.请通过计算判断这辆汽车要回到出发地,是以原来速度省油还是以提速后的速度省油?
-
26.
如图1所示,在
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
中,∠
ACB=90°,
AC=
BC , 过点
C在
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%CE%94%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
外作直线
MN ,
AM⊥
MN于点
M ,
BN⊥
MN于点
N.
-
(1)
求证:
MN=
AM+BN.下边是小李同学的过程,请将他的过程补充完整.
解:(1)证明:∵∠ACB=90°(已知)
∴∠2+∠3=90°(直角的定义)
∵AM⊥MN , BN⊥MN(已知)
∴∠AMC=∠CNB=90°(垂直的定义)
∴在
中
∠3+∠1=180°-∠AMC =90°(三角形内角和定理)
∴∠2=∠ ▲ (同角的余角相等)
在
和
中
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmo%3E%7B%3C%2Fmo%3E%3Cmrow%3E%3Cmtable+columnalign%3D%22left%22%3E%3Cmtr+columnalign%3D%22left%22%3E%3Cmtd+columnalign%3D%22left%22%3E%3Cmo%3E%E2%88%A0%3C%2Fmo%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3Cmtext%3E%E2%96%B2%3C%2Fmtext%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmo%3E%E2%88%A0%3C%2Fmo%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3Cmtext%3E%E2%96%B2%3C%2Fmtext%3E%3Cmn%3E%26nbsp%3B%3C%2Fmn%3E%3C%2Fmtd%3E%3C%2Fmtr%3E%3Cmtr+columnalign%3D%22left%22%3E%3Cmtd+columnalign%3D%22left%22%3E%3Cmo%3E%E2%88%A0%3C%2Fmo%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EM%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmo%3E%E2%88%A0%3C%2Fmo%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmi%3EN%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3C%2Fmtd%3E%3C%2Fmtr%3E%3Cmtr+columnalign%3D%22left%22%3E%3Cmtd+columnalign%3D%22left%22%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi%3EC%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3C%2Fmtd%3E%3C%2Fmtr%3E%3C%2Fmtable%3E%3C%2Fmrow%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
∴
▲ ( )
∴MC=NB , MA= ▲ .(全等三角形的对应边相等)
∴MN=MC+CN=AM+BN
-
(2)
如图2,若过点
C作直线
MN与线段
AB相交,
AM⊥
MN于点
M ,
BN⊥
MN于点
N.(AM>BN),(1)中的结论是否仍然成立?若成立,请说明理由;若不成立,请求出线段 MN , AM与BN之间的数量关系.
![](//tikupic.21cnjy.com/2023/12/06/71/54/7154dfa2e633014ef11a855ff747f41e_202x173.png)