题目

已知三个村庄A，B，C构成一个三角形，且AB=5千米，BC=12千米，AC=13千米．为了方便市民生活，现在△ABC内任取一点M建一大型生活超市，则M到A，B，C的距离都不小于2千米的概率为A. B. C. D. 答案：【答案】C【解析】根据条件作出对应的图象，求出对应的面积，根据几何概型的概率公式进行计算即可．解：在△ABC中，AB＝5，BC＝12，AC＝13，则△ABC为直角三角形，且∠B为直角。则△ABC的面积S＝，若在三角形ABC内任取一点，则该点到三个定点A，B，C的距离不小于2，则该点位于阴影部分，则三个小扇For over one hundred and fifty years, Americans of all social classes have worn blue jeans. 【1】Whether they are worn for work or for fashion today. Strauss' invention continues to be popular not only among Americans but also among people around the world.Levi Strauss was born in Germany in 1829. 【2】 He grew up in Kentucky before moving to New York in 1847. Before becoming an American citizen and moving to the West in 1853, Strauss worked in his brother's dry goods business. This gave him a chance to produce his famous invention. After the gold rush of 1849, Strauss decided to move to the West to seek his fortunes.Strauss did not want to be a person who searched an area for minerals. Instead, he knew he could make a good living by selling supplies to the miners. At first, he planned to sell sewing supplies and cloth. 【3】 When he heard miners complaining that their clothes were easily broken or they usually tore their pockets during mining, he decided to use a special fabric to make pants for the miners. These pants proved so popularthat he quickly ran out of materials to make more.In 1873, Strauss received a letter from a Jewish tailor named Jacob Davis who had invented a process of connecting pockets with copper rivets (铆钉). This made the pants last a long time. Because Davis did not have the money to patent his idea, he offered to share it with Strauss if Strauss would agree to pay for the patent.【4】.By the time Strauss died in 1902, he had made a great contribution to American fashion. 【5】The business has been growing ever since and Levi Strauss' company is now one of the largest clothing companies in the world.A. As a young boy, he moved with his family to the United States.B. Nobody knew what kind of material was suitable.C. He did and Levi jeans have been made with metal rivets ever since.D. However, he did not get much business for those products.E. He also made a great contribution to America's clothing industry.F. Since they were invented by Levi Strauss, they have become a symbol of American consumer culture.G. As the business grew, Strauss got much money from it.