(1) If AD=4, the inscribed triangle with the diameter as the hypotenuse in the circle is a right triangle; If the conditions can be met, the radius of the circle is required to be 5cm, that is, the length of the hypotenuse of the right triangle is 10cm, and the center of the circle falls at the midpoint of the rectangle, while the width of the rectangle is only 4cm, which obviously cannot meet the radius length of 5cm. Therefore, the topic requirements cannot appear.

If AD= 10, it cannot appear.

(2) Using triangle similarity knowledge. The right triangle PDQ, ECQ and BAP are similar, and the quantitative relationship can be found according to CE=2cm. There are only two specifications of right triangle, namely isosceles right triangle and 30-degree right triangle. It can be discussed in two situations.