【简答题】设 , 为直角坐标平面内x轴.y轴正方向上的单位向量,若 ,且 (Ⅰ)求动点M(x,y)的轨迹C的方程; (Ⅱ)设曲线C上两点A.B,满足(1)直线AB过点(0,3),(2)若 ,则OAPB为矩形,试求AB方程.
【简答题】After three days waiting, there was some doubt in the mother's mind______ the police could find her lost child or not.
【简答题】阅读理解。 After spending three days in a wheelchair, I was ready to quit. Not only did I have to battle cracked and uneven pavements, I had to deal with the bad attitude of pedestrians and a cold rain. Bu...
【简答题】设x,y∈R, i , j 为直角坐标平面内x轴y轴正方向上的单位向量,若 a =x i +(y+2) j , b =x i +(y-2) j ,且| a |+| b |=8 (Ⅰ)求动点M(x,y)的轨迹C的方程; (Ⅱ)设曲线C上两点AB,满足(1)直线AB过点(0,3),(2)若 OP = OA + OB ,则OAPB为矩形,试求AB方程.
【简答题】货垛的规范要求主要是指“五距”,即( )、( )、( )、( )、( )。