A dam is 20 meters long, has a trapezoidal cross-section, and has an area of 36 square meters. What is the volume of this dam in cubic meters?
一座拦河大坝长20米，横截面是梯形，面积为36平方米．这座拦河大坝的体积是多少立方米？
<gadget id="calculator">36 * 20</gadget>
<output>720</output>

<result>720</result>