解法探讨及归纳,是回顾知识和提升思维的一种有效方法.下面以2014年益阳市中考第21题为例,说明如下.试题如图1,在直角梯形ABCD中,AB∥CD,AD⊥AB,∠B=60°,AB=10,BC=4,点P沿线段AB从点A向点B运动,设AP=x.(1)求AD的长;(2)点P在运动过程中,是否存在以A、P、D为顶点的三角形与以P、C、B为顶点的 Solution to discuss and induction, is an effective way to review knowledge and enhance thinking.Considering the 21 questions in Yiyang City in 2014 as an example, described as follows.Examples in Figure 1, at right-angle trapezoidal ABCD, AB∥CD, AD ⊥ AB, ∠B = 60 °, AB = 10, BC = 4, the point P moves along the segment AB from point A to point B, let AP = x. (1) Find the length of AD; (2) , Whether there is a triangle whose vertices are A, P, and D and vertices that have vertices P, C, and B