题目

  已知向量和向量，且. （1）求函数的最小正周期和最大值； （2）已知的三个内角分别为，若有，， ，求的长度. 答案：（1）由条件得，得.则函数的周期为，最大值为2.                                        6分 （2）由得，即，由正弦定理得，又，，则.            6分“TODAY is a dream comes true. I have always wanted to be a Grand Slam (大满贯) champion.”These are the words of Chinese tennis player Li Na after she became the first Asian woman to win a Grand Slam final in the French Open on June 4.“People were saying I’m getting old. So this is a great success for such an old woman,” the 29-year-old joked.This is the way that Li usually fights doubts– by being humorous and sharp. “China’s number one sister” is never a pushover (软弱的人). She has a tattoo (纹身). She has dyed (染色) her hair many different colors. And, at the 2008 Beijing Olympics, she told her fans to “shut up” when they got too noisy in their support.Li started to play tennis at the age of 6. She once recalled: “As a child, I felt sad because every day I had to wake up early to practice. After school I had to practice more. I didn’t have time to play.”Luckily, the tough girl didn’t give up, thus making history for Chinese tennis time after time. Now the new champion is already thinking about winning another Grand Slam title. Her next stop is Wimbledon – the European grass court championship that starts later this month. “When you have one title, naturally you will think about another,” she says, not hiding her ambition.“Chinese people are so lacking in confidence on the tennis court. If there is a person like me who can prove we can do it, the other young players in China will feel the same,” she said.小题1:Li Na is _________. A．a basketball playerB．a table tennis player C．a tennis playerD．a soccer player小题2:Li Na is the first Asian woman to win a Grand Slam final in______. A．the Australian Open Tennis ChampionshipsB．the Wimbledon ChampionshipsC．the French OpenD．the American Open小题3:From the passage, we know Li Na is ______. A．outgoingB．fashionableC．toughD．All above小题4:Li Na thinks that Chinese people need _______ in most. A．independenceB．abilityC．confidenceD．ambition