
This unit is about history and traditions. From the opening page, we can know that this unit will introduce the history and traditions around the world. As Marcus Garvey says “A people without the knowledge of their past history, origin and culture is like a tree without roots”, it is important for students to realize the importance and value of knowing the history and traditions and their further meanings. And this part ( listening and speaking ) is divided into two parts: Part A---share views on historic sites, Part B ---talk about a visit to a historic tourist destination. By talking with a foreigner, the speakers introduce the historic attractions and their cultures. Part A is that William, a British student, who was going to visit the Confucius Temple and a Chinese student, Xiao Kong, who was going to the Confucius Temple to meet with the members of the research group, went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. Part B is a conversation between Xiao Yan, a youth hostel receptionist and Paul, a backpacker about the feelings and experience after visiting the Chinese famous tourist attraction Pingyao.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to talk about historic spots and great person.3. Instruct students to use functional sentences of showing one’s excitement, surprise and disappointment.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to discuss with their peers the related topics.3. Enable students to use the functional items of showing one’s excitement, surprise and disappointment.

Features of languages1.Finally, in the 20th century, the southern part of Ireland broke away from the UK, which resulted in the full name we have today: the United Kingdom of Great Britain and Northern Ireland.該句是一個(gè)復(fù)合句。該句主句為:the southern part of Ireland broke away from the UK;which resulted in the full name we have today為which引導(dǎo)的定語(yǔ)從句代指前面整句話的內(nèi)容,we have today為定語(yǔ)從句修飾先行詞name。譯文:最后,在20世紀(jì),愛(ài)爾蘭南部脫離英國(guó),這導(dǎo)致了我們今天有的英國(guó)的全名:大不列顛及北愛(ài)爾蘭聯(lián)合王國(guó)。2.Almost everywhere you go in the UK, you will be surrounded by evidence of four different groups of people who took over at different times throughout history.該句是一個(gè)復(fù)合句。該句主句為:you will be surrounded by evidence of four different groups of people;其中Almost everywhere you go in the UK為讓步狀語(yǔ)從句; who took over at different times throughout history為定語(yǔ)從句修飾先行詞people。譯文:幾乎無(wú)論你走到英國(guó)的任何地方,你都會(huì)發(fā)現(xiàn)歷史上有四種不同的人在不同的時(shí)期統(tǒng)治過(guò)英國(guó)。3.The capital city London is a great place to start, as it is an ancient port city that has a history dating all the way back to Roman times.該句是一個(gè)復(fù)合句。該句主句為:The capital city London is a great place to start; as it is an ancient port city that has a history dating all the way back to Roman times.為原因狀語(yǔ)從句;dating all the way back to Roman times為現(xiàn)在分詞短語(yǔ)作定語(yǔ)修飾history。

This section focuses on "learning about experiencing music Online". This virtual choir is a new form of music performance. Members from all over the world don't need to love to come to a place. Instead, they use the new technology to model the various parts and wonderful virtual harmony group of music in the family. Students need to understand the main meaning of each paragraph. Finding topic sentences is an important way to understand the general idea of a paragraph. After the topic sentence, it is usually the detail sentence that supports and explains the topic sentence. Some paragraphs have obvious subject sentences, for example, the first sentence of the second paragraph is the subject sentence of the paragraph, and the following sentenceStudents need to pay attention to the topic sentences and key sentences, and then pay attention to how the sentences after the meaning explain, explain and support the topic sentences or key sentences before.1.Guide students to learn about experiencing music online2.Guide students to scan and circle the information in the text.3.Guide students to find the numbers and dates to fill in the timeline.4.Guide students to learn more about music by completing the sentences with the correct forms of the words and phrases. And then make a mind map about the outline of the passage.1. Guide students to pay attention to reading strategies, such as prediction, self-questioning and scanning.2. Help students sort out the main meaning of each paragraph and understand the narrative characteristics of "timeline” in illustrative style.3. Lead students to understand the changes that have been caused by the Internet.

(4)Now we have heard a number of outstanding speeches ... 我們已經(jīng)聆聽(tīng)了許多精彩的發(fā)言……(5)Because we wanted the nations of the world, working together, to deal with ... 因?yàn)槲覀兿M澜绺鲊?guó)團(tuán)結(jié)起來(lái)去應(yīng)對(duì)……(6)And if we do not act ... 如果我們不采取行動(dòng)……(7)Now, I share the concerns that have been expressed ... 我也同意對(duì)于……表達(dá)的擔(dān)心(8)Let us show the world that by working together we can ... 讓我們告訴全世界,通過(guò)一起努力我們可以……(9)It is now time for us to ... 是時(shí)候我們……(10)And I have always wished that ... 我一直希望……(11)Thank you for letting me share this day with me.感謝你們和我共度這一天。實(shí)踐演練:假如你是高中生李華,你校將舉辦一次以“音樂(lè)”為主題的演講比賽,請(qǐng)你按照主題,寫(xiě)下你的演講稿。注意:詞數(shù)100左右。First of all, thank you for listening to my speech. My topic is: love music like love yourself.Music is like the air we need to maintain our normal lives around us. You can't imagine how terrible a world without music would be. Movies and TV shows have no music, only dry conversations and scenes; mobile phones only vibrations; streets only noisy crowds; cafes, western restaurants only depressed meals. What a terrible world it is!As a student, I hope we all can enjoy the fun brought by music in our spare time. Instead of just listening to music, we can even make our own music. Let's enjoy the fun of music!Thanks again for your attention!

三、主要工作: 本學(xué)期教務(wù)處繼續(xù)抓好教學(xué)管理,規(guī)范教學(xué)過(guò)程,加強(qiáng)教學(xué)指導(dǎo),加大考核力度。群策群力、千方百計(jì)提高教學(xué)質(zhì)量?! ?、抓好常規(guī)教學(xué)的管理 ?、拧⑶袑?shí)把好教學(xué)流程,規(guī)范教學(xué)秩序。上課期間(包括上晚輔導(dǎo)期間)禁止使用多媒體播放與教學(xué)無(wú)關(guān)的視頻影像?! 、?、規(guī)范教學(xué)過(guò)程,對(duì)備課、上課、作業(yè)批改、課后輔導(dǎo)、單元驗(yàn)收、學(xué)科競(jìng)賽等明確要求,認(rèn)真檢查、指導(dǎo)。檢查作業(yè)批改兩次,教務(wù)處設(shè)專人檢查,記錄。

一、教材分析人教版高中思想政治必修4生活與哲學(xué)第一單元第三課第二框題《哲學(xué)史上的偉大變革》。本框主要內(nèi)容有馬克思主義哲學(xué)的產(chǎn)生和它的基本特征、馬克思主義的中國(guó)化的三大理論成果。學(xué)習(xí)本框內(nèi)容對(duì)學(xué)生來(lái)講,將有助于他們正確認(rèn)識(shí)馬克思主義,運(yùn)用馬克思主義中國(guó)化的理論成果,分析解決遇到的社會(huì)問(wèn)題。具有很強(qiáng)的現(xiàn)實(shí)指導(dǎo)意義。二、學(xué)情分析高二學(xué)生已經(jīng)具備了一定的歷史知識(shí),思維能力有一定提高,思想活躍,處于世界觀、人生觀形成時(shí)期,對(duì)一些社會(huì)現(xiàn)象能主動(dòng)思考,但尚需正確加以引導(dǎo),激發(fā)學(xué)生學(xué)習(xí)馬克思主義哲學(xué)的興趣。三、教學(xué)目標(biāo)1.馬克思主義哲學(xué)產(chǎn)生的階級(jí)基礎(chǔ)、自然科學(xué)基礎(chǔ)和理論來(lái)源,馬克思主義哲學(xué)的基本特征。2.通過(guò)對(duì)馬克思主義哲學(xué)的產(chǎn)生和基本特征的學(xué)習(xí),培養(yǎng)學(xué)生鑒別理論是非的能力,進(jìn)而運(yùn)用馬克思主義哲學(xué)的基本觀點(diǎn)分析和解決生活實(shí)踐中的問(wèn)題。3.實(shí)踐的觀點(diǎn)是馬克思主義哲學(xué)的首要和基本的觀點(diǎn),培養(yǎng)學(xué)生在實(shí)踐中分析問(wèn)題和解決問(wèn)題的能力,進(jìn)而培養(yǎng)學(xué)生在實(shí)踐活動(dòng)中的科學(xué)探索精神和革命批判精神。

二、學(xué)情分析 在校領(lǐng)導(dǎo)的正確領(lǐng)導(dǎo)下,本學(xué)期我校生源比去年有了重大的變化.高一年級(jí)招收了400多名新生,學(xué)校帶來(lái)了新的希望.然而,我清醒地認(rèn)識(shí)到任重而道遠(yuǎn)的現(xiàn)實(shí)是,我校實(shí)驗(yàn)班分?jǐn)?shù)線僅為140分,普通班入學(xué)成績(jī)?nèi)跃痈浇髦袑W(xué)之末.要實(shí)現(xiàn)我校教學(xué)質(zhì)量的根本性進(jìn)步,非一朝一夕之功.實(shí)驗(yàn)班的教學(xué)當(dāng)然是重中之重,而普通班又絕不能一棄了之.現(xiàn)在的學(xué)情與現(xiàn)實(shí)決定了并不是付出十分努力就一定有十分收獲.但教師的責(zé)任與職業(yè)道德時(shí)刻提醒我,沒(méi)有付出一定是沒(méi)有收獲的.作為新時(shí)代的教師,只有付出百倍的努力,苦干加巧干,才能對(duì)得起良心,對(duì)得起人民群眾的期望.

《植物媽媽有辦法》是統(tǒng)編版二年級(jí)上冊(cè)第一單元的一篇講述植物傳播種子的詩(shī)歌,作者運(yùn)用比喻和擬人的修辭手法,以富有韻律感的語(yǔ)言,生動(dòng)形象地介紹了蒲公英、蒼耳、豌豆傳播種子的方法。從植物媽媽的辦法中,能感到大自然的奇妙,激發(fā)學(xué)生了解更多的植物知識(shí)的愿望,培養(yǎng)學(xué)生留心觀察身邊事物的習(xí)慣。教學(xué)過(guò)程中,可以將課文插圖與詩(shī)句相配合,感受三種植物傳播種子的方式。課文插圖畫(huà)面鮮活、直觀、富有兒童情趣,既能激發(fā)學(xué)生的學(xué)習(xí)熱情,又能輔助學(xué)生認(rèn)識(shí)事物,理解重點(diǎn)詞句。 1.認(rèn)識(shí)“植、如”等12個(gè)生字,會(huì)寫(xiě)“法、如”等10個(gè)生字,讀準(zhǔn)多音字“為”和“得”。2.正確、流利、有感情地朗讀課文,背誦課文。3.了解蒲公英、蒼耳、豌豆三種植物傳播種子的方法。4.激發(fā)學(xué)生觀察植物、了解植物知識(shí)、探究植物奧秘的興趣。 1.教學(xué)重點(diǎn):正確、流利、有感情地朗讀課文,背誦課文。了解蒲公英、蒼耳、豌豆三種植物傳播種子的方法。2.教學(xué)難點(diǎn):激發(fā)學(xué)生觀察植物、了解植物知識(shí)、探究植物奧秘的興趣。 2課時(shí)

情境導(dǎo)學(xué)前面我們已討論了圓的標(biāo)準(zhǔn)方程為(x-a)2+(y-b)2=r2,現(xiàn)將其展開(kāi)可得:x2+y2-2ax-2bx+a2+b2-r2=0.可見(jiàn),任何一個(gè)圓的方程都可以變形x2+y2+Dx+Ey+F=0的形式.請(qǐng)大家思考一下,形如x2+y2+Dx+Ey+F=0的方程表示的曲線是不是圓?下面我們來(lái)探討這一方面的問(wèn)題.探究新知例如,對(duì)于方程x^2+y^2-2x-4y+6=0,對(duì)其進(jìn)行配方,得〖(x-1)〗^2+(〖y-2)〗^2=-1,因?yàn)槿我庖稽c(diǎn)的坐標(biāo) (x,y) 都不滿足這個(gè)方程,所以這個(gè)方程不表示任何圖形,所以形如x2+y2+Dx+Ey+F=0的方程不一定能通過(guò)恒等變換為圓的標(biāo)準(zhǔn)方程,這表明形如x2+y2+Dx+Ey+F=0的方程不一定是圓的方程.一、圓的一般方程(1)當(dāng)D2+E2-4F>0時(shí),方程x2+y2+Dx+Ey+F=0表示以(-D/2,-E/2)為圓心,1/2 √(D^2+E^2 "-" 4F)為半徑的圓,將方程x2+y2+Dx+Ey+F=0,配方可得〖(x+D/2)〗^2+(〖y+E/2)〗^2=(D^2+E^2-4F)/4(2)當(dāng)D2+E2-4F=0時(shí),方程x2+y2+Dx+Ey+F=0,表示一個(gè)點(diǎn)(-D/2,-E/2)(3)當(dāng)D2+E2-4F0);

解析:當(dāng)a0時(shí),直線ax-by=1在x軸上的截距1/a0,在y軸上的截距-1/a>0.只有B滿足.故選B.答案:B 3.過(guò)點(diǎn)(1,0)且與直線x-2y-2=0平行的直線方程是( ) A.x-2y-1=0 B.x-2y+1=0C.2x+y=2=0 D.x+2y-1=0答案A 解析:設(shè)所求直線方程為x-2y+c=0,把點(diǎn)(1,0)代入可求得c=-1.所以所求直線方程為x-2y-1=0.故選A.4.已知兩條直線y=ax-2和3x-(a+2)y+1=0互相平行,則a=________.答案:1或-3 解析:依題意得:a(a+2)=3×1,解得a=1或a=-3.5.若方程(m2-3m+2)x+(m-2)y-2m+5=0表示直線.(1)求實(shí)數(shù)m的范圍;(2)若該直線的斜率k=1,求實(shí)數(shù)m的值.解析: (1)由m2-3m+2=0,m-2=0,解得m=2,若方程表示直線,則m2-3m+2與m-2不能同時(shí)為0,故m≠2.(2)由-?m2-3m+2?m-2=1,解得m=0.

問(wèn)題1. 用一個(gè)大寫(xiě)的英文字母或一個(gè)阿拉伯?dāng)?shù)字給教室里的一個(gè)座位編號(hào),總共能編出多少種不同的號(hào)碼?因?yàn)橛⑽淖帜腹灿?6個(gè),阿拉伯?dāng)?shù)字共有10個(gè),所以總共可以編出26+10=36種不同的號(hào)碼.問(wèn)題2.你能說(shuō)說(shuō)這個(gè)問(wèn)題的特征嗎?上述計(jì)數(shù)過(guò)程的基本環(huán)節(jié)是:(1)確定分類標(biāo)準(zhǔn),根據(jù)問(wèn)題條件分為字母號(hào)碼和數(shù)字號(hào)碼兩類;(2)分別計(jì)算各類號(hào)碼的個(gè)數(shù);(3)各類號(hào)碼的個(gè)數(shù)相加,得出所有號(hào)碼的個(gè)數(shù).你能舉出一些生活中類似的例子嗎?一般地,有如下分類加法計(jì)數(shù)原理:完成一件事,有兩類辦法. 在第1類辦法中有m種不同的方法,在第2類方法中有n種不同的方法,則完成這件事共有:N= m+n種不同的方法.二、典例解析例1.在填寫(xiě)高考志愿時(shí),一名高中畢業(yè)生了解到,A,B兩所大學(xué)各有一些自己感興趣的強(qiáng)項(xiàng)專業(yè),如表,

當(dāng)A,C顏色相同時(shí),先染P有4種方法,再染A,C有3種方法,然后染B有2種方法,最后染D也有2種方法.根據(jù)分步乘法計(jì)數(shù)原理知,共有4×3×2×2=48(種)方法;當(dāng)A,C顏色不相同時(shí),先染P有4種方法,再染A有3種方法,然后染C有2種方法,最后染B,D都有1種方法.根據(jù)分步乘法計(jì)數(shù)原理知,共有4×3×2×1×1=24(種)方法.綜上,共有48+24=72(種)方法.故選B.答案:B5.某藝術(shù)小組有9人,每人至少會(huì)鋼琴和小號(hào)中的一種樂(lè)器,其中7人會(huì)鋼琴,3人會(huì)小號(hào),從中選出會(huì)鋼琴與會(huì)小號(hào)的各1人,有多少種不同的選法?解:由題意可知,在藝術(shù)小組9人中,有且僅有1人既會(huì)鋼琴又會(huì)小號(hào)(把該人記為甲),只會(huì)鋼琴的有6人,只會(huì)小號(hào)的有2人.把從中選出會(huì)鋼琴與會(huì)小號(hào)各1人的方法分為兩類.第1類,甲入選,另1人只需從其他8人中任選1人,故這類選法共8種;第2類,甲不入選,則會(huì)鋼琴的只能從6個(gè)只會(huì)鋼琴的人中選出,有6種不同的選法,會(huì)小號(hào)的也只能從只會(huì)小號(hào)的2人中選出,有2種不同的選法,所以這類選法共有6×2=12(種).因此共有8+12=20(種)不同的選法.

(一)例題引入籃球聯(lián)賽中,每場(chǎng)比賽都要分出勝負(fù),每隊(duì)勝1場(chǎng)得2分,負(fù)1場(chǎng)得1分。某隊(duì)在10場(chǎng)比賽中得到16分,那么這個(gè)隊(duì)勝負(fù)場(chǎng)數(shù)分別是多少?方法一:(利用之前的知識(shí),學(xué)生自己列出并求解)解:設(shè)剩X場(chǎng),則負(fù)(10-X)場(chǎng)。方程:2X+(10-X)=16方法二:(老師帶領(lǐng)學(xué)生一起列出方程組)解:設(shè)勝X場(chǎng),負(fù)Y場(chǎng)。根據(jù):勝的場(chǎng)數(shù)+負(fù)的場(chǎng)數(shù)=總場(chǎng)數(shù) 勝場(chǎng)積分+負(fù)場(chǎng)積分=總積分得到:X+Y=10 2X+Y=16

反思感悟用基底表示空間向量的解題策略1.空間中,任一向量都可以用一個(gè)基底表示,且只要基底確定,則表示形式是唯一的.2.用基底表示空間向量時(shí),一般要結(jié)合圖形,運(yùn)用向量加法、減法的平行四邊形法則、三角形法則,以及數(shù)乘向量的運(yùn)算法則,逐步向基向量過(guò)渡,直至全部用基向量表示.3.在空間幾何體中選擇基底時(shí),通常選取公共起點(diǎn)最集中的向量或關(guān)系最明確的向量作為基底,例如,在正方體、長(zhǎng)方體、平行六面體、四面體中,一般選用從同一頂點(diǎn)出發(fā)的三條棱所對(duì)應(yīng)的向量作為基底.例2.在棱長(zhǎng)為2的正方體ABCD-A1B1C1D1中,E,F分別是DD1,BD的中點(diǎn),點(diǎn)G在棱CD上,且CG=1/3 CD(1)證明:EF⊥B1C;(2)求EF與C1G所成角的余弦值.思路分析選擇一個(gè)空間基底,將(EF) ?,(B_1 C) ?,(C_1 G) ?用基向量表示.(1)證明(EF) ?·(B_1 C) ?=0即可;(2)求(EF) ?與(C_1 G) ?夾角的余弦值即可.(1)證明:設(shè)(DA) ?=i,(DC) ?=j,(DD_1 ) ?=k,則{i,j,k}構(gòu)成空間的一個(gè)正交基底.

4.已知△ABC三個(gè)頂點(diǎn)坐標(biāo)A(-1,3),B(-3,0),C(1,2),求△ABC的面積S.【解析】由直線方程的兩點(diǎn)式得直線BC的方程為 = ,即x-2y+3=0,由兩點(diǎn)間距離公式得|BC|= ,點(diǎn)A到BC的距離為d,即為BC邊上的高,d= ,所以S= |BC|·d= ×2 × =4,即△ABC的面積為4.5.已知直線l經(jīng)過(guò)點(diǎn)P(0,2),且A(1,1),B(-3,1)兩點(diǎn)到直線l的距離相等,求直線l的方程.解:(方法一)∵點(diǎn)A(1,1)與B(-3,1)到y(tǒng)軸的距離不相等,∴直線l的斜率存在,設(shè)為k.又直線l在y軸上的截距為2,則直線l的方程為y=kx+2,即kx-y+2=0.由點(diǎn)A(1,1)與B(-3,1)到直線l的距離相等,∴直線l的方程是y=2或x-y+2=0.得("|" k"-" 1+2"|" )/√(k^2+1)=("|-" 3k"-" 1+2"|" )/√(k^2+1),解得k=0或k=1.(方法二)當(dāng)直線l過(guò)線段AB的中點(diǎn)時(shí),A,B兩點(diǎn)到直線l的距離相等.∵AB的中點(diǎn)是(-1,1),又直線l過(guò)點(diǎn)P(0,2),∴直線l的方程是x-y+2=0.當(dāng)直線l∥AB時(shí),A,B兩點(diǎn)到直線l的距離相等.∵直線AB的斜率為0,∴直線l的斜率為0,∴直線l的方程為y=2.綜上所述,滿足條件的直線l的方程是x-y+2=0或y=2.

(2)l的傾斜角為90°,即l平行于y軸,所以m+1=2m,得m=1.延伸探究1 本例條件不變,試求直線l的傾斜角為銳角時(shí)實(shí)數(shù)m的取值范圍.解:由題意知(m"-" 1"-" 1)/(m+1"-" 2m)>0,解得1<m<2.延伸探究2 若將本例中的“N(2m,1)”改為“N(3m,2m)”,其他條件不變,結(jié)果如何?解:(1)由題意知(m"-" 1"-" 2m)/(m+1"-" 3m)=1,解得m=2.(2)由題意知m+1=3m,解得m=1/2.直線斜率的計(jì)算方法(1)判斷兩點(diǎn)的橫坐標(biāo)是否相等,若相等,則直線的斜率不存在.(2)若兩點(diǎn)的橫坐標(biāo)不相等,則可以用斜率公式k=(y_2 "-" y_1)/(x_2 "-" x_1 )(其中x1≠x2)進(jìn)行計(jì)算.金題典例 光線從點(diǎn)A(2,1)射到y(tǒng)軸上的點(diǎn)Q,經(jīng)y軸反射后過(guò)點(diǎn)B(4,3),試求點(diǎn)Q的坐標(biāo)及入射光線的斜率.解:(方法1)設(shè)Q(0,y),則由題意得kQA=-kQB.∵kQA=(1"-" y)/2,kQB=(3"-" y)/4,∴(1"-" y)/2=-(3"-" y)/4.解得y=5/3,即點(diǎn)Q的坐標(biāo)為 0,5/3 ,∴k入=kQA=(1"-" y)/2=-1/3.(方法2)設(shè)Q(0,y),如圖,點(diǎn)B(4,3)關(guān)于y軸的對(duì)稱點(diǎn)為B'(-4,3), kAB'=(1"-" 3)/(2+4)=-1/3,由題意得,A、Q、B'三點(diǎn)共線.從而入射光線的斜率為kAQ=kAB'=-1/3.所以,有(1"-" y)/2=(1"-" 3)/(2+4),解得y=5/3,點(diǎn)Q的坐標(biāo)為(0,5/3).

1.兩圓x2+y2-1=0和x2+y2-4x+2y-4=0的位置關(guān)系是( )A.內(nèi)切 B.相交 C.外切 D.外離解析:圓x2+y2-1=0表示以O(shè)1(0,0)點(diǎn)為圓心,以R1=1為半徑的圓.圓x2+y2-4x+2y-4=0表示以O(shè)2(2,-1)點(diǎn)為圓心,以R2=3為半徑的圓.∵|O1O2|=√5,∴R2-R1<|O1O2|<R2+R1,∴圓x2+y2-1=0和圓x2+y2-4x+2y-4=0相交.答案:B2.圓C1:x2+y2-12x-2y-13=0和圓C2:x2+y2+12x+16y-25=0的公共弦所在的直線方程是 . 解析:兩圓的方程相減得公共弦所在的直線方程為4x+3y-2=0.答案:4x+3y-2=03.半徑為6的圓與x軸相切,且與圓x2+(y-3)2=1內(nèi)切,則此圓的方程為( )A.(x-4)2+(y-6)2=16 B.(x±4)2+(y-6)2=16C.(x-4)2+(y-6)2=36 D.(x±4)2+(y-6)2=36解析:設(shè)所求圓心坐標(biāo)為(a,b),則|b|=6.由題意,得a2+(b-3)2=(6-1)2=25.若b=6,則a=±4;若b=-6,則a無(wú)解.故所求圓方程為(x±4)2+(y-6)2=36.答案:D4.若圓C1:x2+y2=4與圓C2:x2+y2-2ax+a2-1=0內(nèi)切,則a等于 . 解析:圓C1的圓心C1(0,0),半徑r1=2.圓C2可化為(x-a)2+y2=1,即圓心C2(a,0),半徑r2=1,若兩圓內(nèi)切,需|C1C2|=√(a^2+0^2 )=2-1=1.解得a=±1. 答案:±1 5. 已知兩個(gè)圓C1:x2+y2=4,C2:x2+y2-2x-4y+4=0,直線l:x+2y=0,求經(jīng)過(guò)C1和C2的交點(diǎn)且和l相切的圓的方程.解:設(shè)所求圓的方程為x2+y2+4-2x-4y+λ(x2+y2-4)=0,即(1+λ)x2+(1+λ)y2-2x-4y+4(1-λ)=0.所以圓心為 1/(1+λ),2/(1+λ) ,半徑為1/2 √((("-" 2)/(1+λ)) ^2+(("-" 4)/(1+λ)) ^2 "-" 16((1"-" λ)/(1+λ))),即|1/(1+λ)+4/(1+λ)|/√5=1/2 √((4+16"-" 16"(" 1"-" λ^2 ")" )/("(" 1+λ")" ^2 )).解得λ=±1,舍去λ=-1,圓x2+y2=4顯然不符合題意,故所求圓的方程為x2+y2-x-2y=0.

一、情境導(dǎo)學(xué)在一條筆直的公路同側(cè)有兩個(gè)大型小區(qū),現(xiàn)在計(jì)劃在公路上某處建一個(gè)公交站點(diǎn)C,以方便居住在兩個(gè)小區(qū)住戶的出行.如何選址能使站點(diǎn)到兩個(gè)小區(qū)的距離之和最小?二、探究新知問(wèn)題1.在數(shù)軸上已知兩點(diǎn)A、B,如何求A、B兩點(diǎn)間的距離?提示:|AB|=|xA-xB|.問(wèn)題2:在平面直角坐標(biāo)系中能否利用數(shù)軸上兩點(diǎn)間的距離求出任意兩點(diǎn)間距離?探究.當(dāng)x1≠x2,y1≠y2時(shí),|P1P2|=?請(qǐng)簡(jiǎn)單說(shuō)明理由.提示:可以,構(gòu)造直角三角形利用勾股定理求解.答案:如圖,在Rt △P1QP2中,|P1P2|2=|P1Q|2+|QP2|2,所以|P1P2|=?x2-x1?2+?y2-y1?2.即兩點(diǎn)P1(x1,y1),P2(x2,y2)間的距離|P1P2|=?x2-x1?2+?y2-y1?2.你還能用其它方法證明這個(gè)公式嗎?2.兩點(diǎn)間距離公式的理解(1)此公式與兩點(diǎn)的先后順序無(wú)關(guān),也就是說(shuō)公式也可寫(xiě)成|P1P2|=?x2-x1?2+?y2-y1?2.(2)當(dāng)直線P1P2平行于x軸時(shí),|P1P2|=|x2-x1|.當(dāng)直線P1P2平行于y軸時(shí),|P1P2|=|y2-y1|.

一、情境導(dǎo)學(xué)前面我們已經(jīng)得到了兩點(diǎn)間的距離公式,點(diǎn)到直線的距離公式,關(guān)于平面上的距離問(wèn)題,兩條直線間的距離也是值得研究的。思考1:立定跳遠(yuǎn)測(cè)量的什么距離?A.兩平行線的距離 B.點(diǎn)到直線的距離 C. 點(diǎn)到點(diǎn)的距離二、探究新知思考2:已知兩條平行直線l_1,l_2的方程,如何求l_1 〖與l〗_2間的距離?根據(jù)兩條平行直線間距離的含義,在直線l_1上取任一點(diǎn)P(x_0,y_0 ),,點(diǎn)P(x_0,y_0 )到直線l_2的距離就是直線l_1與直線l_2間的距離,這樣求兩條平行線間的距離就轉(zhuǎn)化為求點(diǎn)到直線的距離。兩條平行直線間的距離1. 定義:夾在兩平行線間的__________的長(zhǎng).公垂線段2. 圖示: 3. 求法:轉(zhuǎn)化為點(diǎn)到直線的距離.1.原點(diǎn)到直線x+2y-5=0的距離是( )A.2 B.3 C.2 D.5D [d=|-5|12+22=5.選D.]

1.直線2x+y+8=0和直線x+y-1=0的交點(diǎn)坐標(biāo)是( )A.(-9,-10) B.(-9,10) C.(9,10) D.(9,-10)解析:解方程組{■(2x+y+8=0"," @x+y"-" 1=0"," )┤得{■(x="-" 9"," @y=10"," )┤即交點(diǎn)坐標(biāo)是(-9,10).答案:B 2.直線2x+3y-k=0和直線x-ky+12=0的交點(diǎn)在x軸上,則k的值為( )A.-24 B.24 C.6 D.± 6解析:∵直線2x+3y-k=0和直線x-ky+12=0的交點(diǎn)在x軸上,可設(shè)交點(diǎn)坐標(biāo)為(a,0),∴{■(2a"-" k=0"," @a+12=0"," )┤解得{■(a="-" 12"," @k="-" 24"," )┤故選A.答案:A 3.已知直線l1:ax+y-6=0與l2:x+(a-2)y+a-1=0相交于點(diǎn)P,若l1⊥l2,則點(diǎn)P的坐標(biāo)為 . 解析:∵直線l1:ax+y-6=0與l2:x+(a-2)y+a-1=0相交于點(diǎn)P,且l1⊥l2,∴a×1+1×(a-2)=0,解得a=1,聯(lián)立方程{■(x+y"-" 6=0"," @x"-" y=0"," )┤易得x=3,y=3,∴點(diǎn)P的坐標(biāo)為(3,3).答案:(3,3) 4.求證:不論m為何值,直線(m-1)x+(2m-1)y=m-5都通過(guò)一定點(diǎn). 證明:將原方程按m的降冪排列,整理得(x+2y-1)m-(x+y-5)=0,此式對(duì)于m的任意實(shí)數(shù)值都成立,根據(jù)恒等式的要求,m的一次項(xiàng)系數(shù)與常數(shù)項(xiàng)均等于零,故有{■(x+2y"-" 1=0"," @x+y"-" 5=0"," )┤解得{■(x=9"," @y="-" 4"." )┤
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