In the parallelogram ABCD, P, Q, R, S are on the sides AB, BC, CD, DA respectively, and AP=DR. If the area of parallelogram ABCD is 16 square centimeters, try to find the area of quadrilateral PQRS?
在平行四边形ABCD中，P、Q、R、S分别在边AB、BC、CD、DA上，且AP=DR．如果平行四边形ABCD的面积是16平方公分，试求四边形PQRS的面积？
<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<result>8</result>