一、选择题(本大题共 10 小题, 每小题 3 分, 满分 30 分, 在每小题给出的四个选项中, 只有一项是符合题目要求的. )
-
-
-
-
-
A . 4,4
B . 7,2
C . 6,4
D .
-
A . 图象是一条射线
B . 图象必经过点
C . 图象经过第一、三象限
D .
随
的增大而减小
-
A . 直角三角形
B . 等腰三角形
C . 等腰直角三角形
D . 等腰三角形或直角三角形
-
-
9.
(2024八下·黄埔期末)
如图, 对折矩形纸片
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
, 使
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
重合, 得到折痕
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
, 把纸片展平, 再一次折叠纸片, 使点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3C%2Fmath%3E)
落在
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
上, 并使折痕经过点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
, 得到折痕
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
, 同时得到线段
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
. 若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
交点为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EG%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%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+mathvariant%3D%22normal%22%3EG%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3E%26nbsp%3B%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%26nbsp%3B%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%26nbsp%3B%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%26nbsp%3B%3C%2Fmi%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmath%3E)
![](//tikupic.21cnjy.com/2024/10/01/f8/2f/f82fe394d882cb0e9ac763a806d5c6fc_m_239x158.png)
A . 1
B . 2
C .
D .
-
10.
(2024八下·黄埔期末)
如图 1, 在 Rt
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
中,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3E%E2%88%A0%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E90%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmo%3E%E2%88%98%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
, 点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
是
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的中点, 动点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3C%2Fmath%3E)
从点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
出发沿
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
运动到点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
停止. 设点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3C%2Fmath%3E)
的运动路程为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
的面积为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
的图象如图 2 所示, 则 Rt
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
的面积为 ( )
![](//tikupic.21cnjy.com/2024/10/01/ac/11/ac11aadfdacca9fc136139ef3adba0cc_m_611x217.png)
A . 10
B . 16
C . 20
D . 40
二、填空题 (本大题共 6 小题, 每小题 3 分, 满分 18 分. )
-
-
12.
(2024八下·黄埔期末)
某项竞赛, 有 15 名同学参加, 参赛选手的成绩各不相同, 一名同学想要知道自己是否进入前 8 名, 只需了解自己的成绩以及全部成绩的
. (填平均数、中位数或众数)
-
13.
(2024八下·黄埔期末)
如图, 一垂直地面的木杆, 在离地面 12 米处折断, 木杆顶端落在离木杆底端 5 米处, 则木杆折断之前的高度为
米.
![](//tikupic.21cnjy.com/2024/07/31/64/7d/647d56f5149fa232384f145d00f7b8d2_169x168.png)
-
-
15.
(2024八下·黄埔期末)
如图, 已知一次函数
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Ek%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Eb%3C%2Fmi%3E%3C%2Fmath%3E)
的图象经过点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E2%2C2%3C%2Fmn%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmath%3E)
和点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmn%3E4%2C0%3C%2Fmn%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmath%3E)
, 一次函数
的图象经过点
, 则关于
的不等式组
的解集为.
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3E%26nbsp%3B%3C%2Fmi%3E%3C%2Fmath%3E)
![](//tikupic.21cnjy.com/2024/10/01/b2/b9/b2b966184da9a29bf3e4db109234adbf_m_243x239.png)
-
16.
(2024八下·黄埔期末)
如图, 在矩形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
和矩形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
中,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
相交于点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
相交于点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
, 连接
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
, 并延长
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
相交于点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3C%2Fmath%3E)
, 若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
, 则下列结论正确的是
。
①
;
②
;
③
;
④连接
, 若
, 四边形
与四边形
的面积之比为
.
![](//tikupic.21cnjy.com/2024/10/01/af/30/af305d3186de7bb0ec499da6da0a1c71_m_224x253.png)
三、解答题(本大题共 9 小题, 满分 72 分. 解答应写出文字说明、证明过程或演算步骤. )
-
-
-
-
-
(2)
求一次函数
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Ek%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Eb%3C%2Fmi%3E%3C%2Fmath%3E)
图象与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
轴的交点坐标.
-
20.
(2024八下·黄埔期末)
如图, 在 ▱
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
中,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
是它的一条对角线,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
是线段
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
上两点, 若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
.求证: 四边形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
是平行四边形.
![](//tikupic.21cnjy.com/2024/10/01/9e/56/9e5605d8b3286a0af0cf7f1ebac777c4_m_223x139.png)
-
21.
(2024八下·黄埔期末)
如图, 正方形网格中的每个小正方形边长都为 1 , 每个小格的顶点叫做格点, 四边形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
以格点为顶点.
![](//tikupic.21cnjy.com/2024/10/01/ff/89/ff89c17b5ae082255279d044de23124f_m_195x195.png)
-
(1)
求四边形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
的周长;
-
(2)
证明:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3E%E2%88%A0%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E90%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmo%3E%E2%88%98%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
.
-
-
-
-
(3)
若乙队员成绩方差为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmfrac%3E%3Cmrow%3E%3Cmn%3E8%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E7%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfrac%3E%3C%2Fmath%3E)
, 现选派其中一名队员参赛, 你认为应选哪名队员?并说明理由.
-
-
(1)
画出动点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3C%2Fmath%3E)
横纵坐标
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3C%2Fmath%3E)
满足的函数对应的图象;
-
(2)
当点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3C%2Fmath%3E)
异于点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3C%2Fmath%3E)
时, 设
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%E2%96%B3%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EO%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EP%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3C%2Fmath%3E)
的面积为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3ES%3C%2Fmi%3E%3C%2Fmath%3E)
.
①当
时, 求
的面积
的值;
②求
关于
的函数解析式.
-
24.
(2024八下·黄埔期末)
某建筑公司现有
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
两工地需要租车运土,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3C%2Fmath%3E)
工地需要 12 台,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
工地需要 18 台;租车公司现有甲型车 10 台, 乙型车 20 台可供选择,每天租金价格如右表。
| 甲型车租金 | 乙型车租金 |
工地
| 800 元 台 | 600 元 台 |
工地
| 600 元/台 | 300 元/台 |
-
(1)
设
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3C%2Fmath%3E)
工地租甲型车
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
台, 租乙型车
台;则
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3C%2Fmath%3E)
工地租甲型
台, 租乙型车
台 (用含
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
的式子表示)。
-
(2)
设该公司每天的总租金为
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3C%2Fmath%3E)
元, 请求出
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ey%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
的函数解析式并写出
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3Ex%3C%2Fmi%3E%3C%2Fmath%3E)
的取值范围。
-
(3)
在(2)条件下, 公司如何租车才能使得每天总租金最少?最少租金是多少?请说明理由.
-
25.
(2024八下·黄埔期末)
如图 1,把一个含
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsup%3E%3Cmrow%3E%3Cmn%3E45%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmo%3E%E2%88%98%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3C%2Fmath%3E)
的直角三角板
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
和一个正方形
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
摆放在一起,使三角板的直角顶点和正方形的顶点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
重合, 连接
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
, 点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3C%2Fmath%3E)
与
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
分别是
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%E3%80%81%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
中点, 连接
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
。
![](//tikupic.21cnjy.com/2024/10/01/48/94/489438384fb41d754edb2778f299dd25_m_561x155.png)
-
(1)
如图 1, 点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%E3%80%81%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
分别在正方形的边
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%E3%80%81%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
上, 连接
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%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+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%E3%80%81%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
的数量关系是
;
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3E%E3%80%81%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EN%3C%2Fmi%3E%3C%2Fmath%3E)
的位置关系是
;
-
(2)
如图 2, 将图 1 中直角三角板
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
绕点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
顺时针旋转, 当点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3C%2Fmath%3E)
落在线段
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
上时, 其他条件不变, (1) 中结论是否仍然成立, 若成立, 请证明结论, 若不成立, 请说明理由.
-
(3)
如图 3, 将图 1 中直角三角板
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EF%3C%2Fmi%3E%3C%2Fmath%3E)
绕点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3C%2Fmath%3E)
顺时针旋转
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsup%3E%3Cmrow%3E%3Cmi+mathvariant%3D%22normal%22%3En%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmo%3E%E2%88%98%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmsup%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3En%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E90%3C%2Fmn%3E%3Cmo%3E%29%3C%2Fmo%3E%3C%2Fmath%3E)
, 其他条件不变, 若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EA%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EB%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E5%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3EE%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3EC%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmath%3E)
, 直接写出线段
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmi+mathvariant%3D%22normal%22%3EM%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3ED%3C%2Fmi%3E%3C%2Fmath%3E)
的最小值.