题目

如图，一艘轮船以每小时20海里的速度沿正北方向航行，在A处测得灯塔C在北偏西30°方向，轮船航行2小时后到达B处，在B处测得灯塔C在北偏西60°方向．当轮船到达灯塔C的正东方向的D处时，求此时轮船与灯塔C的距离．（结果保留根号） 答案：【考点】解直角三角形的应用-方向角问题． 【专题】计算题． 【分析】根据三角形外角和定理可求得BC的值，然后放到直角三角形BCD中，借助60°角的正弦值即可解答． 【解答】解：由题意得∠CAB=30°，∠CBD=60°， ∴∠ACB=30°， ∴BC=BA=40海里， ∵∠CDB=90°， ∴sin∠CBD=． ∴sin60°==． ∴CD=BC×=40×（海里）任务型阅读。Many young people want to be famous players like Yao Ming. They think they will own (拥有) everything when they are famous. And then they will do what they want. For example, when you are famous, you can do something good for schools and charities (慈善机构). You can also do some work to help others. However, as a famous person, it is not easy. You will meet many problems. If you are famous, people will follow you everywhere. They are around you every day, but you’ll never know who your real (真正的) friends are. You’ll lose your own (自己的) life. In fact, many famous people are not happy. They feel that the life before was more interesting.根据短文内容，完成任务。1.Who wants to be a famous players like Yao Ming ?_________________ _____.2.Do the famous people lose their own life ?_________________ _____.3.Are the famous people happy all the time?_________________ _____.4.将画线句子译成汉语。______ _________________.