已知椭圆C: x2a2+y2b2=1 (a>b>0)的短轴长为2,过上顶点E和右焦点F的直线与圆M:x2+y2﹣4x﹣2y+4=0相切.
(Ⅰ)求椭圆C的标准方程;
(Ⅱ)若直线l过点(1,0),且与椭圆C交于点A,B,则在x轴上是否存在一点T(t,0)(t≠0),使得不论直线l的斜率如何变化,总有∠OTA=∠OTB (其中O为坐标原点),若存在,求出 t的值;若不存在,请说明理由.
细草微风岸,危樯独夜舟。____,____。____,____。飘飘何所似,天地一沙鸥。(杜甫《旅夜书怀》)
如图所示为定值电阻R1和R2中的I—U关系图.若将R1和R2并联后接在电压为6V的电源两端,则通过R1和R2的电流之比为____,R1和R2两端的电压之比为____,R1和R2消耗的功率之比为____.若将R1和R2串联在电压为6V的电路中,则R1和R2两电阻消耗的功率之比为____.
C
Hello! My name is Jack.I am from England.Now I am in China with my parents.I like China.I like Chinese food,too.I have breakfast at home.I eat an egg,some bread and porridge(粥) for breakfast.I don't like milk.I have no time to go home for lunch,so I have it at school.The lunch at school is very good.I often have noodles and dumplings.Noodles are my favourite food. Sometimes I have different foods for lunch.I eat rice,meat and vegetables.I always go home early in the afternoon.Then I do my homework.I have supper with my parents.Sometimes we go out to have dinner with our friends.We are happy in China.