综观近年中考试题,凡涉及动点移动的考题,一般都会出现动点与函数图象上的特殊点,或某些特殊图形上的特殊点构成的三角形,由此引发求线段长或三角形面积最大值,或在某特定条件下动点的运动时间等问题,解题时大多要考虑运用相似三角形的判定定理及其性质来解决.例1(2011舟山中考)已知直线y=kx+3(k<0)分别交x轴、y轴于A、B两点,线段 Looking at the examination questions in recent years, where moving points involved in moving questions, usually appear on the moving point and the special point on the image, or some special graphics on the formation of the triangle, which led to the line length or the largest triangle area Value, or under certain conditions, the movement time of the moving point, etc., most of the problems to be solved when considering the use of similar triangles to determine the theorem and its nature to solve. Example 1 (2011 Zhoushan test) known line y = kx +3 ( k <0) were submitted to the x-axis, y-axis at A, B two-point, line segment