题目

如图，在平面直角坐标系中，直线＋2与x轴、y轴分别交于A、B两点，以AB为边在第二象限内作正方形ABCD. （1）求点A、B的坐标，并求边AB的长； （2）求点D和点C的坐标； （3）你能否在x轴上找一点M，使△MDB的周长最小?如果能，请求出M点的坐标；如果不能，说明理由． 答案：解：（1）当y=0时，x=-4，则A的坐标（-4，0）， 当x=0时，y=2，则B的坐标（0，2），∴； （2）过D做线段DE垂直x轴，交x轴于E，则△DEA≌△AOB， ∴DE=AO=4，EA=OB=2，∴D的坐标为（-6，4），同理可得C的坐标为（-2，6）；（3）作B关于x轴的对称点B′，连接MB′，与x轴的交点即为点M， 则B′（0，-2），设直线MB′根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。Travel in Montreal's underground cityMontreal is the second largest city in Canada with a population of over 4,100,000 people. When we go shopping in Montreal in Canada, we may find that 1.. Why? That's because many people do their shopping under the ground. With 4,350 hotel rooms, 2,727 apartments, 930 shops, 68 subway stations,9 fitness centers, 3 skating rinks, 2 libraries，and a small church，2.. If you live in one of the underground apartments, 3.. Because of outdoor temperatures that may drop to–35℃ in winter, 4.. The underground city is thought as an important tourist attraction by most Montreal travel guidebooks. If you like, 5.. In 1962, while breaking ground for the city's first subway, the idea for an underground shopping mall was born at the same time.A. more than 4. 5 square miles make up the world's largest underground cityB. people prefer to stay under the ground in order to get away from the coldnessC. you cannot do sports in Montreal's underground cityD. it is not crowded at all in the shopping mallsE. you can take the subway to work and do the shoppingF. Montreal remains an important center of industry.G. you can spend a week in the underground city