2020～2022N广版英语周报答案

17.解:(1)因为 cos Acos B+cosC=sin2 Asin b,A+B+C=r,所以 cos Acos B-cos(A+B)=sin2 Asin b,1分所以 cos Acos B- cos Acos B+ sin asin b=sin2 Asin b2分所以 sin Asin h=2 sin Acos Asin B.分又A∈(0,x),B∈(0,x),所以sinA≠0,且sinB≠04分所以cosA=5分所以A=56分(2)因为A+B=C,A+B+C=r,A所以B=6,C=2·…8分又因为b所以如=610分所以a=311分所以△ABC的面积S=1×a×b=1×3×1=12分

【参考范文】One day, Spotty returned from his daily walk with a broken leg. Appearing exhausted, he came to myroom and sat near me, the leg bleeding. I called my mother and she quickly tied a bandage around his leg andgave him food to eat. I was very upset. But the next day, Spotty followed me wherever I went happily asusual though he limped a bit. After this incident my relation with Spotty became more intense. I reallyadmired him a lot for his courageAlmost a year later, one midnight we heard Spotty barking breathlessly. We rushed out and saw himbarking continuously, heading somewhere. After some time Spotty became quiet. I patted him on his backand came inside. The next morning, my heart skipped a beat when I didn't see Spotty. I searched for him ineach and every corner but in vain. And this time he had gone and would never come back. I cried and waitedfor him. But there were no signs of him and I only say him looking at me with his sparking eyes in my dream

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