数学参考答案:
预习作业(1)圆
自主学习: 见九上课本P106-P107
尝试练习: 1、上,外,上
2、(1)内,(2)5,(3)外
3、圆内,圆上,圆外
4、圆上,,
5、以点P为圆心,6cm为半径的圆
6、C
巩固练习: 1、(1)B在圆上,C在圆外,D在圆外
(2)B在圆内,C在圆外,D在圆上
(3)B在圆内,C在圆上,D在圆内
2、提示:连接AC,找AC的中点O,连接OD,OB。说明OB=OA=OC=OD。
3、提示:连接EM,DM。说明EM=BM=CM=DM
圆的有关概念
自主学习:见九上课本P108-P109
尝试练习:1、╳2、╳ 3、√4、╳ 5、╳ 6、√
7、提示:说明△COB≌△DOA
8、提示:连接OA,OB,说明△OAC≌△OBD
巩固练习:1、∠A=28°
2、BC=8
3、提示:连接OC,解得OC=5,AB=10
P110 5、∠B=55°
6、提示:说明△AOD≌△BOC
7、提示:说明∠OCD=∠OAB
8、提示:连接OD,则OD=AB=2,再说明四边形OFDE是矩形,从而EF=OD=2.
预习作业(2)圆的对称性
自主学习:见九上课本P111-P112
尝试练习:1、90° 2、60° 3、60° 4、60°
5、相等,提示:说明AC=BC
巩固练习:1、AC=BD,连接OC,OD说明:△OCE≌△ODE
2、BE 的度数为120°
3、提示:连接AC,BD说明△ACE与△BDF为等腰三角形,从而得到AE=AC,BF=BD
圆的对称性(2)
学习内容:例1,例2 (1)OA=5 (2)3≤OP≤5
达标检测:1. 2. 3.AM= 4.连接OP作垂直于op的弦 5.OP=3 6.R=5
7. 8. 1 9. 1或7 10.(1)AO=10 (2)2 11. 26
5.3圆周角(1)
尝试练习
(1)∠BDC=___35__°,(2)∠BOC=___70____°
(3)如图,点A、B、C在⊙O上, 若∠BAC=60°,求∠BOC=__120____°; 若∠AOB=90°,求∠ACB=_45_____
(4)例题:见课本
达标检测
1、延长CD交圆于点E,方法与例4相同
2、与∠BOC相等的是:∠BDC, ∠BAC, ∠ECA, ∠OBA
3、∠ABD=35 4、∠AOB=__80_____,∠OAB=___50__
5、∠ABD=_____30___6、与△ABD相似的三角形有_△CED,_ △AEC
圆周角2
同弧或等弧所对的圆周角都等于所对的圆心角的一半
直角
过
直径或半圆所对的圆周角等于90°
90°所对的弦是直径
略
50° 100°
提示:连接OC,OE AE=5
例题
AD=
∠CEB=100°
略
提示:连接AD证垂直平分线
提示:连接CD,AC=
确定圆的条件
无数个
无数个 垂直平分线上
不能 结论:不在同一直线上的三点可以确定一圆
三角形的三个顶点确定一个圆这个圆叫做三角形的外接圆
如果圆上有三个不重合的点,则这三点构成的三角形叫做圆的内接三角形
外接圆的圆心叫做三角形的外心
到三角形三个顶点距离相等
锐角三角形:外心在圆内
直角三角形:外心在圆上
钝角三角形:外心在圆外
尝试解决
内接 外接
一四错误,三正确
r=5, S=25π
略
例题精讲
例1.1.100°
2.100°
3.120°或60°
例二.提示:连接OB,OC过O点作OD垂直于BC用垂径定理解 r=3 r= EMBED Equation.KSEE3 \* MERGEFORMAT
例三.连接AD并延长叫BC于D点,连接OB,OC
r= EMBED Equation.KSEE3 \* MERGEFORMAT
例四.略
课堂检测
略
1)r=6.5
2)r= EMBED Equation.KSEE3 \* MERGEFORMAT
3)AB= EMBED Equation.KSEE3 \* MERGEFORMAT 或 EMBED Equation.KSEE3 \* MERGEFORMAT
英语参考答案:
五
完型填空
1-5 DBABD 6-10 CBBDB 11-15 ADCDC
1-5ACDAC 6-10 BACBA 11-15 CCDBD
阅读理解
1-5DABCD
阅读表达
1.all over
2.你可以使用英特网代替图书室
3.An E-mail is a way to send messages.
4.It’s much quicker and cheaper than sending a letter.
5.Quick easy and interesting ----- that’s the Internet
缺词填空
1-5 broken , throw, left, ready ,usually 6-10 seats, belongs mistakes voice successful
书面表达
Dear principal:
I would like to recommend my classmates as the new leader of our school station.I think he will been excellent leader because he has many good qualities.
He is always ready to help others. He often helps us us with our homework and explains things to us. At .school he helps other students .For example,he shows the Grade 7 students how to use the library.
He is energetic and often does things for us. He is good at making or planning things. Last term, he hosted a charity and he has the ability to be the leader. He can get on well with his classmates.
Everyone thinks he has the qualities to be a good leader of the radio station. We hope you agree with us..
六
完形填空16~20 ADBBD 21~25 ADABD 26~30 DBDAD
阅读理解31—35 CBDAB 36-40 DCDAB
阅读表达
1. share with 2. 过了一会儿,狮子向他们慢慢走来,然后越跑越快。
3.The man shouted in a loud voice and began to run away.
4.The girl asked us if we knew what the man had said
5. People have different ways to express love.
缺词填空
1. understand 2.same 3. advantages 4. important 5. seems
6. after 7. provide 8. until 9. deal 10 contol
七、书面表达(满分20分)Dear Mum and Dad,Time flies! I've been here for nearly a year. I'm very pleased to find that our school is really a good one. The students in our school is really a good one. The students in our school work hard at their lessons. We take an active part in activities. We are friendly to each other and always ready to help each other.The teachers here all enjoy their work and they love their students. They work hard and do what they can do to help us. And the students respect their teachers. We get on well with each other. The students in our school try their best to keep the school yard clean and tidy. They never throw waste about or pick the flowers.In a word, I am deeply impressed by the harmonious atmosphere in this school. I love my new school.Yours,Frank
七
ABACA DAABC
DCADC BACBB ABDCB
1. Italy world
2. He passed away on September 6th, 2007.
3. 无论我们选择什么,我们都应该全身心投入。
4. It took 7 years of study and hard work before I made my first