题目

设为坐标原点，抛物线的焦点为，点在上，.（1）求的方程；（2）过点的直线与交于，两点，若与圆相切，求的面积 答案：【答案】（1）（2）16【解析】（1）结合已知条件，根据抛物线定义列出方程可得解；（2）设出直线方程，与抛物线联立，结合面积公式和韦达定理即可得解.解：（1）由抛物线定义，点到准线的距离①∵点在抛物线上，∴ ②由①②解得，∴抛物线方程为.（2）设直线方程为，，，∵直线与圆相切，∴I hear many parents saying that their teenagers are rebellious(反叛的). I wish it were so. At your age you ought to be growing away from your parents. You should be learning to stand on your own feet. But take a good look at the present rebellion. It seems that teenagers are all taking the same way of showing that they disagree with their parents. Instead of striking out bravely on their own, most of them are trying to seize at another’s hands for safety. They say they want to dress as they please. But they all wear the same clothes. They set off in new directions in music. But somehow reason for thinking or acting in thus-and-such way is that the cords is doing it. They have come out of their cocoon—into a larger cocoon. It has become harder and harder for a teenager to stand up against the popularity wave and to go his or her own way. Industry has firmly opened up a teenager market. These days every teenager can learn from newspapers and TV what a teenager should have and be. And many of today’s parents have come to award high marks for the popularity of their children. All this adds up to great difficulty for the teenager who wants to find his or her own path. But the difficulty is worth getting over. The path is worth following. You may want to listen to classical music instead of going to a party. You may want to collect rocks when everyone else is collecting records. You may have some thoughts that you don’t care to share at once with your classmates. Well, go to it. Find yourself. Be yourself. Popularity will come—with the people who respect you for who you are. That’s the only kind of popularity that really counts. 73. The writer’s purpose in writing this passage is mainly to tell _____________ . readers how to be popular in the world teenagers how to learn to decide things for themselves parents how to control and guide their children people how to understand and respect each other 74. According to the writer, many teenagers think they are brave enough to act on their own, but in fact, most of them ______________. have much difficulty in understanding each other have too much confidence in themselves dare not do things in their own way are very much afraid of getting lost 75. During the teenager years, one should learn to __________ . become different from others in as many ways as possible find one’s real self get into the right reason and become popular rebel against parents