【题目】如图1,四边形 ABCD 是直角梯形,∠A=90°,AB=8cm,AD=24cm,BC=26cm,点 P从 A 出发,以1cm/s 的速度向D运动,点 Q 从 C 点同时出发,以3cm/s 的速度向 B运动,其中一个动点到达端点时,另一动点也随之停止运动,从运动开始,经过多少时间,四边形 PQCD 成 [Problem] As shown in Fig. 1, the quadrilateral ABCD is a right trapezoid with ∠A = 90 °, AB = 8cm, AD = 24cm and BC = 26cm. Point P moves from A to D at 1cm / s, C at the same time starting to 3cm / s speed B movement, one of the moving point to reach the endpoint, the other moving point also will stop moving from the beginning of exercise, after how much time, quadrilateral PQCD into