一、选择题:本题共8小题,每小题5分,共40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,
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A . 0
B .
C . a
D . 3a
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A . 2
B .
C . 3
D . 5
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A . 第一象限角都是锐角
B . 三角形的内角必是第一、二象限的
C . 不相等的角终边一定不相同
D . 不论是用角度制还是弧度制度量一个角,它们与扇形的半径的大小无关
二、多选题:本题共3小题,每小题6分,共18分.在每小题给出的选项中,有多项符合题目要求.全部选对的得6分,部分选对的得部分分,有选错的得0分.
三、填空题:本题共3小题,每小题5分,共15分.
四、解答题:本题共5小题,共77分.解答应写出必要的文字说明、证明过程及演算步骤.
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(3)
已知
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsub%3E%3Cmi%3ES%3C%2Fmi%3E%3Cmn%3E5%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E24%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
, 求
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsub%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E%2B%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmn%3E4%3C%2Fmn%3E%3C%2Fmsub%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
.
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17.
(2024高三上·威信月考)
某中学高三年级某班50名学生期中考试数学成绩的频率分布直方图如图所示,成绩分组区间为:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E80%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E90%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E90%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E100%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E100%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E110%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E110%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E120%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E120%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E130%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%29%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E130%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E140%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmfenced+close%3D%22%5D%22+open%3D%22%5B%22%3E%3Cmrow%3E%3Cmn%3E140%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E150%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
.其中
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi%3Eb%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi%3Eb%3C%2Fmi%3E%3Cmo%3E%E2%88%92%3C%2Fmo%3E%3Cmi%3Ec%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
, 且
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ec%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmi%3Ea%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
.该50名学生的期中考试物理成绩统计如下表:
![](//tikupic.21cnjy.com/ct20241o/27/7a/277ab56f996490394cb427205d23ac25.png)
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(1)
根据频率分布直方图,求
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3Ea%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi%3Eb%3C%2Fmi%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmi%3Ec%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
的值,并估计数学成绩的平均分(同一组数据用该区间的中点值代表);
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(2)
若数学成绩不低于140分的为“优”,物理成绩不低于90分的为“优”,已知本班中至少有一个“优”的同学总数为6人,从数学成绩为“优”的同学中随机抽取2人,求两人恰好均为物理成绩为“优”的概率.
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(1)
求证:
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EE%3C%2Fmi%3E%3Cmi%3EF%3C%2Fmi%3E%3Cmo%3E%2F%3C%2Fmo%3E%3Cmo%3E%2F%3C%2Fmo%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
平面
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
;
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(2)
若
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EA%3C%2Fmi%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3Cmsqrt%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmsqrt%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3ED%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E12%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3EB%3C%2Fmi%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmi%3EC%3C%2Fmi%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
, 求直线CD与平面EFC所成角的正弦值.
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(2)
是否存在过点
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmi%3EP%3C%2Fmi%3E%3Cmfenced+open%3D%22%28%22+close%3D%22%29%22%3E%3Cmrow%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E%2C%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmfenced%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
的直线l与椭圆C相交于不同的两点M,N,且满足
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmover+accent%3D%22true%22%3E%3Cmrow%3E%3Cmi%3EO%3C%2Fmi%3E%3Cmi%3EM%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmo+stretchy%3D%22true%22%3E%E2%83%97%3C%2Fmo%3E%3C%2Fmover%3E%3Cmo%3E%E2%8B%85%3C%2Fmo%3E%3Cmover+accent%3D%22true%22%3E%3Cmrow%3E%3Cmi%3EO%3C%2Fmi%3E%3Cmi%3EN%3C%2Fmi%3E%3C%2Fmrow%3E%3Cmo+stretchy%3D%22true%22%3E%E2%83%97%3C%2Fmo%3E%3C%2Fmover%3E%3Cmo%3E%3D%3C%2Fmo%3E%3Cmn%3E2%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmath%3E)
(O为坐标原点)若存在,求出直线l的方程:若不存在,请说明理由.