例1如图1,点A、B的坐标为(2,0)、(0,1),若将线段AB平移至A_1B_1,则a+b的值为().A.2 B.3C.4 D.5[点拨]由平移前后B点的纵坐标分别为1、2,A点的横坐标分别为2、3,可得B点向上平移1个单位,A点向右平移1个单位,则A点也要向上平移1个单位,B点也要向右平移一个单位,所以b=1,a=1,故a+b=2.故选A.[反思]线段的平移就是线段两端点的平移,两端点的横坐标、纵坐标在平移前后的变化完全相同. Example 1 In Figure 1, the coordinates of points A and B are (2,0) and (0,1). If line AB is shifted to A_1B_1, the value of a+b is ().A.2 B.3C. 4 D.5[Dial] The ordinates at the B points before and after the translation are 1, 2 respectively, and the abscissas at the A point are 2, 3 respectively. The B point can be translated 1 unit upwards and the A point is shifted 1 unit to the right. , then A point should also be translated 1 unit upward, B point should also be translated to the right one unit, so b = 1, a = 1, so a + b = 2. So choose A. [reflection] the translation of the line segment is the line segment The translation of the two ends of the point, the change of the abscissa and ordinate of the two ends are exactly the same before and after the translation.