【判断题】通过半径为圆弧编制程序,半径取负值时刀具移动角应大于等于180度。( )
【简答题】已知椭圆 x 2 a 2 + y 2 b 2 =1(a>b>0) 的离心率为 6 3 ,长轴长为2 3 . (1)求椭圆的方程; (2)试直线y=kx+1交椭圆于不同的两点A、B,以AB为直径的圆恰过原点O,求直线方程.
【单选题】根据以下内容回答题: Adam Smith,writing in the 1770s,was the first person to see the importance of the divi-sion of labor and to explain part of its advantages.He gives as an example the process by which pins w...
A.
take advantage of the division of the labor
B.
introduce the division of labor into England
C.
understand the effects of the division of labor
D.
explain the causes of the division of labor
【简答题】In face of failure, it is the most important to keep up good state of mind. A .不填; a B . a 不填 C . the 不填 D .不填; the
【单选题】根据以下内容回答题: Adam Smith,writing in the 1770s,was the first person to see the importance of the divi-sion of labor and to explain part of its advantages.He gives as an example the process by which pins w...
A.
take advantage of the division of the labor
B.
introduce the division of labor into England
C.
understand the effects of the division of labor
D.
explain the causes of the division of labor
【简答题】已知椭圆: x 2 a 2 + y 2 b 2 =l(a>b>0)的一个顶点坐标为B(0,1),若该椭圆的离心率等于 3 2 . (1)求椭圆的方程. (2)Q是椭圆上位于x轴下方的一点,F 1 F 2 分别是椭圆的左、右焦点,直线QF 1 的倾斜角为 π 6 ,求△QF 1 F 2 的面积; (3)以B为直角顶点作椭圆的内接等腰直角三角形ABC,判断这样的三角形存在吗?若存在,有几个?若不存在,...
【简答题】大学教育 大学教育是人类文明的体现,大学教育水平则反映社会的文明程度。中国的大学教育近些年快速发展,有助于普及高等教育。大学的数量和大学生的人数增长迅速,在2010年,在校大学生人数就已经达到了3000万。大学教育为社会培养了大量的专业人才,他们是国家未来发展的核心动力,因此,大学教育极大地促进了社会的进步。但中国的大学教育也面临着不少的问题,如专业设置不合理、教学质量下降、毕业生就业难等。 重点...
【简答题】如图,已知椭圆 x 2 a 2 + y 2 b 2 (a>b>0)的离心率 e= 6 3 ,短轴长为2. (1)求椭圆的方程. (2)已知定点E(-1,0),若直线y=kx+2(k≠0)与椭圆交于C、D两点.问:是否存在k的值,使以CD为直径的圆过E点?请说明理由.
【单选题】It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it.
【单选题】通过半径为圆弧编制程序,半径取负值时刀具移动角应 ( ) 。