您所在的当前位置：高中数学试题 >

平面向量数量积的意义

> 在直角△ABC中，CD是斜边AB上的高，则下列等式不成立的是（　　） A．| AC |2= AC • AB B．| BC |2= BA • BC C．| AB |2= AC • CD D．| CD |2= ( AC • AB )×( BA • BC ) | AB |2

问题：

发布时间：2024-09-07

在直角△ABC中，CD是斜边AB上的高，则下列等式不成立的是（　　）

A．|

AC

|2=

AC

•

AB

B．|

BC

|2=

BA

•

BC

C．|

AB

|2=

AC

•

CD

D．|

CD

|2=

(

AC

•

AB

)×(

BA

•

BC

)

|

AB

|2

参考答案：

提问用户：mu***xlg

可能感兴趣的题目：

1 下列少数民族和其民族习俗搭配正确的是 A.蒙古族-雪顿节 B.藏族-那达慕 C.傣族-泼水节 D.乌孜别克族-春节
2 反映某种股票的涨跌情况应选择 A.扇形图 B.折线图 C.直方图 D.都可以
3 一个做匀加速直线运动的物体，当它的速度由v增至2v时，发生的位移为S 1；当它的速度由2v增至3v时，发生的位移为S 2，则（） A．S1:S2=2:3　　 B．S1:S2=5:3　　 C．S1:S2=1:4　 D．S1:S2=3:5
4 在某未知溶液中检验出含有Ba 2+、NO 3 －，且溶液的pH＝1。某学生还需鉴定此溶液中是否大量存在：①Al 3+；②NH 4 +；③Fe 2+；④Cl －；⑤AlO 2 －；⑥SO 4 2－，其实这些离子中有一部分不必再鉴定就能加以否定，你认为不必再鉴定的离子组是 [ ] A．③⑤⑥ B．④⑤⑥ C．①②⑤ D．①③④
5 阅读理解。 A Tight Situation Sometimes funny memories are the most special way to remember a beloved lover. It helps take away some of the feeling of loss. Before he passed away, my husband loved to share this story with our friends. Now, it makes a smile to share this story with you. Our neighbor"s son was getting married at a church, and we were invited. We immediately rushed out to the store, and I bought a nice pink dress with a jacket. The dress was a little tight, but I had a month before the June 30 wedding and I would lose a few pounds. June 29 came and, of course, I had not lost a single pound; in fact, I had gained two. But, I thought a new girdle (收腹健美裤) would solve my problem. So on the way to the wedding, we stopped once again at the store. I ran in and told the clerk I needed a size large girdle. The clerk found the box with the described girdle, marked "L", and asked if I would like to try it on. "Oh, no, large will fit just right. I won"t need to try it on." The next morning was hot, so I waited to get dressed until about forty-five minutes before time to go. I opened the girdle box only to find a new ＄49.95 girdle in a size small. Since it was too late to find another one and the dress wouldn"t fit right without a girdle, a fight broke out between me and the girdle. Have you ever tried to shake twenty pounds of potatoes into a five-pound bag? Finally, my husband, laughing like crazy, got hold of each side and shook me down into it, and I was ready to go. As we walked into the church, he asked if I could make it. Now, he was getting worried because I was breathing funny. I told him that it would last one hour, twenty-two minutes and eight-and-one-half seconds-the minister blessed everything except my girdle! My knees were blue and my legs lost all the feeling. My husband was asking questions and trying to comfort me. As soon as the minister pronounced them married, I rushed out with my husband. "Please, just get me out of here!" I said. We ran out to our car, and once there he opened the front and back passenger doors against the next car. Right there, before God, human and the wedding party, I took off that girdle. When the girdle flew out of my hand and landed under the car next to ours, my husband was laughing so hard and we drove away. Over the years, he and I had often wondered what the people of that church thought the next morning when they found ＄49.95, size small girdle in their parking lot. 1. When she was telling the story, she ______. A. was sorry for her husband"s death B. was happy to share her funny memories C. was wondering who had picked up the girdle D. still couldn"t forget the trouble on that day 2. She still bought the tight pink dress, because she thought ______. A. she would save some money B. she would gain a few pounds C. she would lose some weight D. she looked thinner in the dress 3. Which statement is true according to the story? A. She changed the girdle for a larger size. B. They tried hard to pour lots of potatoes into a small bag. C. She put on the dress without the girdle in the end. D. She managed to put on the girdle with her husband"s help. 4. The title "A Tight Situation" really means ______. A. she was dressed in a tight girdle B. she dressed herself in a limited time C. she got herself embarrassed D. the wedding lasted longer than she expected 5. The writer"s purpose of writing this story is ______. A. to tell an interesting experience B. to prove her husband"s love C. to describe her tight girdle D. to describe her unspeakable feeling
6 ________ the flower looks! A.What beautiful B.How beautiful C.What a beautiful D.How beautifully
7 根据量子理论，每个光子的动量为p=h/λ（式中h为普朗克常量，λ为光子的波长）．当光照射到物体表面上时，不论光子被物体吸收还是被物体表面反射，光子的动量都发生了改变，因此对物体表面产生压力，这种压力称为光压．图21是科学家用来测量光压的仪器．图中两个圆片中，a是涂黑的，而b是光亮的．当光线照射到a上时，可以认为光子全部被吸收，而当光线照射到b上时，可以认为光子全部被反射．分别用光线照射在a或b上，由于光压的作用，都可以使该装置以悬丝为轴发生旋转，旋转的角度可以借助于和悬丝一起旋转的小平面镜M进行观察和测量．已知a、b两个圆片的半径都为r，用频率为ν的激光束同时照射a、b两个圆片，设激光束与圆面垂直，覆盖整个圆片表面，单位时间内垂直于光传播方向的单位面积上通过的光子个数为n，真空中的光速为c．求：a、b两个圆片所受的光压各多大？
8 广东沿海滩涂围垦，需要经过筑堤、挖渠等工程措施和种植适应性植物等生物措施改造，4—5年后才能种植粮食作物。据此完成14～15题。小题1: 改造滩涂所种植的适应性植物应 A．耐湿 B．耐旱 C．耐盐 D．抗倒伏小题2:若缩短滩涂改造时间，需投入更多的 A．花费 B．农家肥 C．农药 D．淡水
9 Can you explain ________ the sun goes down in the west? A．why is it that B．why it is that C．how it is that D．how is it that
10 2007年4月14日，我国在西昌成功发射了第五颗北斗导航试验卫星，这标志着我国全球卫星导航系统——北斗卫星导航系统的建设又向前迈了一步。回答1～3题。小题1:北斗卫星导航系统除能够提供精确的定位、测速外，还能够提供的服务包括 ①授时 ②通信服务 ③农作物长势预测 ④气温异常监测 A．①② B．③④ C．①④ D．②③ 小题2:在应用地理信息系统进行城市道路规划时，最适合作为基准图件的是 A．行政区划图 B．人口密度图 C．遥感影像 D．商业分布图小题3:一支地理考察队所用手持式北斗导航定位系统信号接收机显示的如右界面，据此判断该考察队可能 A．在喜马拉雅山测量珠峰高度 B．在塔里木盆地勘探石油 C．在柴达木盆地调查地质构造 D．在河西走廊寻找地下水

在直角△ABC中，CD是斜边AB上的高，则下列等式不成立的是（ ） A．| AC |2= AC • AB B．| BC |2= BA • BC C．| AB |2= AC • CD D．| CD |2= ( AC • AB )×( BA • BC ) | AB |2

可能感兴趣的题目：

在直角△ABC中，CD是斜边AB上的高，则下列等式不成立的是（　　）

A．|

AC

|2=

AC

•

AB

B．|

BC

|2=

BA

•

BC

C．|

AB

|2=

AC

•

CD

D．|

CD

|2=

(

AC

•

AB

)×(

BA

•

BC

)

|

AB

|2