(本小題滿分10分)
在平面直角坐標(biāo)系xOy中，點(diǎn)A(－1,－2)、B(2,3)、C(－2,－1).
(1)求以線段AB、AC為鄰邊的平行四邊形兩條對(duì)角線的長(zhǎng)；
(2)設(shè)實(shí)數(shù)t滿足()·=0，求t的值.
（1）、；（2）.解析:
(1)先求出,然后可以求出平行四邊形的對(duì)角線對(duì)應(yīng)的向量的模分別為,
(2)先求出和的坐標(biāo)，然后利用()·=0，建立關(guān)于t的方程,從而求得t的值.
解：（1）方法一：由題設(shè)知，則
……2分
所以
故所求的兩條對(duì)角線的長(zhǎng)分別為、……5分
（2）由題設(shè)知：=(－2,－1)，.……7分
由()·=0，得：，
從而所以……10分
練習(xí)冊(cè)系列答案
相關(guān)習(xí)題

科目：初中英語 來源：湖北省襄陽市2011年中考英語試題 題型：001

聽力測(cè)試(本大題滿分25分，每小題1分)

第一節(jié)

聽下面的8段短對(duì)話。每段對(duì)話后有一個(gè)小題，從每小題A、B、C三個(gè)選項(xiàng)中選出一個(gè)最佳答案。聽完每段對(duì)話后，你有10秒鐘的時(shí)間來回答有關(guān)小題和閱讀下一小題。每段對(duì)話只讀一遍。

1．What's Jim's favourite fruit?

A．Apples．

B．Pears．

C．Bananas．

2．Where does the woman want to go?

A．To the hospital．

B．To the bank．

C．To the bookstore．

3．How often does Tom surf the Internet?

A．Every day．

B．Never．

C．Once a week．

4．What does the man mean?

A．He doesn't think Class 2 will win．

B．He thinks Class 2 will win．

C．He hopes Class 2 will win．

5．How does the man learn English?

A．By reading aloud．

B．By making flashcards．

C．By listening to tapes．

6．Why didn't the woman answer the phone?

A．She wasn't in．

B．She didn't want to．

C．She was washing her hair．

7．What time is it now?

A．It's 6∶40．

B．It's 7∶15．

C．It's 7∶45．

8．Which might be the reason why Victor failed the driver's test?

A．He was too nervous．

B．He didn't practice at all．

C．He didn't have enough time to practice．

第二節(jié)

下面你將聽到5段對(duì)話或獨(dú)白．每段對(duì)話或獨(dú)白后有幾個(gè)小題，從每小題A、B、C三個(gè)選項(xiàng)中，選出一個(gè)與你所聽到的對(duì)話或獨(dú)白內(nèi)容相符的問題的答案。聽每段對(duì)話或獨(dú)白前，你都有10秒鐘的時(shí)間閱讀相關(guān)小題；聽完后，每小題將給出5秒鐘的作答時(shí)間，對(duì)話或獨(dú)白讀兩遺。

聽第一段材料，回答第9至11小題。

9．What is Kathy doing for vacation?

A．Studying at home．

B．Traveling abroad．

C．Doing a part-time job．

10．How does she feel these days?

A．Bored．

B．Excited．

C．Tired．

11．Where is she most probably going on vacation?

A．To Hawaii．

B．To Switzerland．

C．Somewhere cold．

聽第二段材料，回答第12至14小題。

12．What's the possible rala6onship(關(guān)系)between the two speakers?

A．Friends．

B．Husband and wife．

C．Strangers．

13．How long has it been since the two speakers saw each other lint time?

A．A few months．

B．About a year．

C．A few years．

14．Whose leg was broken?

A．The woman's．

B．The man's wife's．

C．The man's son's．

聽第三段材料，回答第l5至17小題。

15．Why do they collect the rubbish along the river?

A．To stop the fiver from being polluted．

B．To sell it for money．

C．To see the river every day．

16．How many volunteers do they have?

A．12．

B．16．

C．28．

17．When do they do the volunteer work?

A．At 7∶30 every morning．

B．After lunch at noon．

C．After dinner every evening．

聽筆四段材料，同答第18至20小顥．

18．What's the man doing?

A．Selling the house．

B．Looking for a house．

C．Asking for a job．

19．Why does the woman want to sell the house?

A．She wants to move to the countryside．

B．She wants to move abroad．

C．She hopes to buy a bigger one．

20．How much does the house cost?

A．＄ 9,680．

B．＄ 9,860．

C．＄ 9,618．

聽第五段材料，回答第21至25小題．

21．Where did the story happen?

A．In the school．

B．In the restaurant．

C．In the library．

22．What did the man order for his meal?

A．Some noodles．

B．The cheapest things．

C．The most expensive food．

23．What did the man say when he left there?

A．He was buying a newspaper．

B．He was buying some beer．

C．He was getting some money at the bank．

24．Was the man the boy's father?

A．Yes, he was．

B．No, be wasn't．

C．We don't know．

25．When did the man ask the boy to come in and sit at his table?

A．After he left．

B．At two o'clock．

C．After paying for the meal．

查看答案和解析>>

科目：初中英語 來源：2012-2013學(xué)年江蘇省附屬初中九年級(jí)二模英語卷（解析版） 題型：其他題

短文填空 根據(jù)短文內(nèi)容及首字母提示，補(bǔ)全空格內(nèi)單詞，使短文完整、通順。（請(qǐng)?jiān)诖痤}卡上寫出完整單詞）（本大題共10小題，滿分10分）

A blind boy sat on the steps of a building with a hat by his feet. He held up a sign which said: “I am blind, please help.” There were only a few coins in the h  1. .

A man was w  2.  by. He took a few coins from his pocket and dropped them into the hat. He then took the sign, wrote some words on the other side of it. Then he put the sign back s__3.__ that everyone who walked by would see the new words.

Soon the hat began to fill up. A lot m  4.  people were giving money to the blind boy. That afternoon the man who had c  5. the sign came to see how things were. The boy recognized his footsteps and asked, “Were you the one who changed my sign this morning? What did you write?”

The man said, “I only wrote the truth. I said what you said but in a d  6.  way.”

What he had written was: “Today is a beautiful day, b  7.  I cannot see it.”

Do you think the first sign and the second sign were saying the same thing? Of course b8.  signs told people the boy was blind. But the first sign s 9.  said the boy was blind. The second sign told people they were so l  10.  that they were not blind. Should we be surprised that the second sign was more effective?

 

查看答案和解析>>

科目：初中英語 來源：2011-2012學(xué)年江蘇省興化市初三中考模擬英語試卷（解析版） 題型：閱讀理解

閱讀短文，按要求完成短文后的各項(xiàng)任務(wù)。（本大題共5小題，滿分10分）

There are many advantages and disadvantages for being a musician.

The biggest advantage is being able to do something you love. (1)You will have the        chance to travel to many different ______ and meet a lot of different ______. That will open up your eyes.

However, there are also disadvantages of being a professional(專業(yè)的) musician. (2)One of the biggest disadvantages for most musicians is that they don’t always have enough money. Most of the time, you will be looking for jobs. Sometimes you won’t be able to find a good job easily. Another disadvantage is the place you live in. If you want to be a musician, you usually have to move to an area that has a lot of jobs, such as New York City. The cost of living in these areas is usually very high. The third disadvantage is that you can’t have a stable（穩(wěn)定的） family life. Different jobs will take a musician to different places, so most musicians are unable to have a regular family.

1.在(1) 空白處分別填入一個(gè)適當(dāng)?shù)脑~使句意完整、上下文通順。

2.將(2)處的英文翻譯成中文

3.在文中找出與It’s difficult for some musicians to find a good job sometimes.的同義句：

4.回答問題：How many disadvantages for being a musician are there in this text?

5.寫出文中最能表達(dá)該短文主題的句子。

 

查看答案和解析>>

科目：初中英語 來源：2011屆江蘇省如皋市初三下學(xué)期第一次月考英語卷 題型：其他題

閱讀與回答問題。（本大題共5小題，每小題2分，滿分10分）

   Jeff Keith has only one leg. When he was 12 years old, Jeff had cancer. Doctors had to cut off most of his right leg. Every day Jeff puts on an artificial(man-made) leg. The leg was plastic. With the plastic leg, Jeff can ski, ride a bicycle, swim and play soccer. He can also run.

   When he was 22 years old, Jeff Keith ran across the United States, from the East to the West. He started running in Boston on April 1. He stopped running in Los Angeles. He ran 5,190 kilometres; that’s about 26 kilometres each day. Jeff wore out 36 pairs of running shoes and five plastic legs.

   Jeff stopped in cities on the way to Los Angeles. In every city people gave Jeff money. The money was not for Jeff. It was for the American Cancer Society. The American Cancer Society used the money to learn about cancer.

   On the way to Los Angeles, Jeff talked to people about cancer. He also talked about being disabled. Jeff is disabled, but he can do many things: he skis, swims, plays soccer, and runs. He finished college and is studying to be a lawyer. Jeff says, “People can do anything they want to do. I want people to know that. I ran not only for disabled people. I ran for everybody.”

1. Why does Jeff have one leg left?

   __________________________________________________________________________

2. What did Jeff do with the money he got on the way to Los Angeles?

   __________________________________________________________________________

3. What does Jeff want to be in the future?

   __________________________________________________________________________

4.How long did it take Jeff to run from Boston to Los Angeles?

   __________________________________________________________________________

5. What does the story want to tell us?(請(qǐng)自擬一句話作答)

   __________________________________________________________________________

 

查看答案和解析>>

同步練習(xí)冊(cè)答案