【正文】 ? ? ? ? ? ? ? ? ?, 所以 1 2 8 3 7 32 3 2 3ABCS ? ? ? ?。 (2) 求使 14fx?成立的 x 的取值集合 【答案】 解 : (1) 41)212cos2 32(sin21)3sinsin3cos(coscos)( ?????????? xxxxxxf ?? 41)32(.414123sin21)32(41)62sin(21 ??????????? ???? ffx 所以. (2)由 (1)知 , )2,2()62(0)62sin(4141)62sin(21)(f ?????? kkxxxx ??????????? .),12,127(.),12,127( ZkkkZkkkx ???????? ???????? 所以不等式的解集是： 29． （ 2020年高考天津卷（文）） 在 △ ABC 中 , 內角 A, B, C 所對的邊分別是 a, b, c. 已知 sin 3 sinb A c B?, a = 3, 2cos 3B?. (Ⅰ ) 求 b 的值 。 2020 年全國各地高考文科數學試題分類匯編：三角函數 一、選擇題 1 ． （ 2020 年高考大綱卷（文）） 已知 a 是第二象限角 , 5si n , cos13aa??則（ ） A． 1213? B． 513? C． 513 D． 1213 【答案】 A 2 ． （ 2020 年高考課標 Ⅰ 卷（文）） 函數( ) (1 c os ) si nf x x x??在[ , ]???的圖像大致為 【答案】 C。 (Ⅱ ) 求sin 2 3B ????????的值 . 【答案】 30． （ 2020 年高考廣東卷（文）） 已知函數 ( ) 2 c o s ,12f x x x R???? ? ?????. (1) 求3f ???????的值 。 33． （ 2020 年高考福建卷（文）） 如圖 ,在等腰直角三角形OPQ?中 ,90OPQ??,22OP?,點 M在線段PQ上 . (1)若3OM?,求 PM的長 。 (Ⅱ) 設 3a? ,S 為 △ ABC 的面積 ,求 3cos cosS B C? 的最大值 ,并指出此時 B 的值 . 【答案】 36． （ 2020 年高考四川卷（文） ） 在 ABC? 中 ,角 ,ABC 的對邊分別為 ,abc,且 3c os ( ) c os sin ( ) sin ( ) 5A B B A B A c? ? ? ? ? ?. (Ⅰ) 求 sinA 的值 。 (Ⅱ) 不畫圖 ,說 明函數()y f x?的圖像可由sinyx?的圖象經過怎樣的變化得到 . 【答案】 解 :(1)3sincos3cossinsin)( ?? xxxxf ??? xxxx cos2 3sin23cos2 3sin21sin ????? )6sin(3)6sin()2 3()23( 22 ?? ??? xx 當1)6sin( ????x時 ,3)( min ??xf,此時)(,234,2236 Zkkxkx ??????? ????? 所以 ,)(xf的最小值為3?,此時 x 的集合},234|{ Zkkxx ?? ??. (2)xy sin?橫坐標不變 ,縱坐標變?yōu)樵瓉淼?倍 ,得xy sin3?。 若零點在區(qū)間的端點 ,則僅在區(qū)間左或右端點處得一個區(qū)間含 3 個零點 ,其它區(qū)間仍是 2 個零點 。 not to have conquered, but to have fought well. 2, the plain is the background of life. Live a plain life, give up on themselves is not a coward, but the wise answers。t get into a blind alley, don39。m afraid he turned to it as a joke to tell don39。 loss of sink, Eritrea pany. When you are in adversity, may wish to change a point of view to think everything over to the good Think, because good mentality decided the fate of the! 7, people are tired, rest。s mouth, because words will reduce its importance。am, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and goodness, helping others. Instead of accusing the society, as into one。t let everyone like you, so also do not want to do. Life is too short to go crazy to love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their own emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expensive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of wisdom. 16, life is not perfect, sometimes, growth is not a cry, not an eyeful of tears, there is no trace of emotion, there is no gleam of hope, no desire, no action, no static, there is only one kind of downward sinking feeling, sink A murky? 6? 7? 6? 7 sink? 6? 7? 6? 7 toward the bottom of the sink. 17, in some way, do not go, you will not know the other side scenery is beautiful. To you is not good, you do not mind too much, no one has an obligation to you。t despair, the coast is still, if the fate of the withered petals of the beautiful, please do not sink, the spring is still, life will always be endless trouble, please don39。 choose a simple, is choose to be happy. The plex world like a Significance of pride. Hope is the ornate palace, outside people admiring the magnificent, living in the deep knowledge of living it to pay the price. Simple world as a simple log cabin outside ridiculed shabby, the heart is willing to go live to know the joy. Suffering and joy is their own choice. 22, learn how to use a single powerful heart, let the past be the past, let the future e. Life is really the end of the end of an eagle is flying wings, life is constantly pursuit. Don39。 failing to do not frown, laugh it laugh. Results Don39。t really dare to adhere to the principle. No rade, constantly put on reworking an emergency meeting to Comrade Zhen to speak louder, management tube too strict. Remember in Dongguan Street, 400 meters long cement concrete surface layer, because of various reasons, the smoothness of the poor in the bottom cavity, covering film traces and car imprinting quality problems, * * * inquiries, immediately rushed to the scene to understand and verify the situation, the convening of the management office, the construction units, supervision units, construction units, construction units construction time is tight, the economic loss and other reasons to intercede ******** unmoved. He said, now a popular word, to the discipline and rules quite in front, there are no rules Radius, you construction team not accordance with the technical specifications, quality problems, it must be to carry out rectification. Engineering quality responsibility be weightier than Mount Tai, if we manage to this matter Pavement quality quantity are placed the matter, we this time to learn two regulations have what use? Still what is the Communist Party? Finally, in his insisted, the road after rework, to solve these problems. In the construction of the new rades and the project all the colleagues efforts, after four months of fighting, the project the main project was finally pleted and passed inspection. Thousands of miles of ice, thousands of miles Piao, this is a splendid and romantic scene. But snow for the highway, it is a disaster, a serious threat to the traffic safety. This year, a month, a century of cold wave swept from North to south, and the snow blowing to Guangdong, but also to bear the blow To * * * * the highway. In January o