2022英语周报答案0

8.【必备知识】本题考查的知识是“掌握正弦定理、余弦定理,并能解决一些简单的三角形度量问题”【关键能力】本题考查逻辑思维能力和运算求解能力【解题思路】(1)2cosA=正弦定理bcos C ccos BAA∈(0,m)(2)解法一a=√3且A正弦定理√3sin(B )三角恒等变换sin(2B-)令=B b3∈(0,)→in6e(,12√3b c的取值范围sin 8解法二余弦定理,b2 e≤12-…22 的范围解:(1)由正弦定理得2csAsin Bcos C sin Ccos B sin(B C)因为B C=丌-A,所以sin(B C)=sinA,所以2cosA=1,即cosA(3分)又A∈(0,m),所以A=可(2)解法一由正弦定理知, n A sin B sin C2,(5分所以sB snC如B b 3)c 2sin B 2sinC 2sin Bsin C2sin Bsin(B 2)V3 sin(B (7分)sin(2B-)因为A=,所以B∈(0,2)(8分)令=B g,则θ∈(,),则sine∈(,1(9分)√3sine3 sin e2, sin esin(20-) 2-cos26 14sime-123(12分)解法因为a=3,4=3,所以由余弦定理知62 c2-b=3(6分)所以be≤3,(b c)2=3bc 3,(7分)k 1=5×√be k3-3b 的取值范剧一5, )故(12分)解题关键》求解本题的关键:一是熟记两角和、差的正弦公式,对所求式子进行转化;二是活用正弦定理、余弦定理;三是注意三角形内角的取值范围

第二节书面表达【写作思路】根据试题要求,考生需要写一篇记叙文,记述身边一位值得尊敬和爱戴的人。首先考生需要介绍自己最尊敬和爱戴的人是谁,简单地介绍一下他(她)。然后,陈述为什么他(她)值得尊敬和爱戴。最后,可以对前文进行一个总结,使文章结构严谨。本文的写作重点在"尊敬和爱戴的原因",考生可围绕这个要点适当拓展,从性格特点、处事风格等方面展开写作。【范文赏读】The most beloved and respected person around me is my teacher, Ms LiThough she has been teaching English for twenty years, she is still passionateabout teaching. She is kind and considerate towards us just like our dear motherWe all respect her because she always tries new ways to make her classes livelyand interesting. Hardworking and knowledgeable, she is one of the best teachersin our school. When we have a problem, we will turn to her for help. She alwaystalks to us patiently and helps us to find a solution. In our eyes, she is not onlyour teacher, but also our best friend. Those are why she deserves our respect【亮点词句】亮点词汇: beloved, respected, be passionate about, be consideratetowards, turn to sb. for help, in one's eyes亮点句式:Why引导的表语从句( why she deserves our respect)

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