A triangle and a parallelogram have the same area and the same base. The height of the parallelogram is 20 cm, what is the height of the triangle in cm?
一个三角形与一个平行四边形的面积相等，底也相等．平行四边形的高是20cm，三角形的高是多少cm．
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<result>40</result>