Cut out the largest triangle from a parallelogram with an area of 9 square decimeters, what is the area of this triangle in square decimeters?
从一个面积是9平方分米平行四边形上剪下一个最大的三角形，这个三角形的面积是多少平方分米．
<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>