The upper degree of a trapezoid is 6 decimeters, the lower base is 10 decimeters, and the height is 6 decimeters. With the upper base of the trapezoid as the base, draw a largest triangle inside. What is the area of this triangle in square decimeters?
一个梯形的上度是6分米，下底是10分米，高是6分米，以梯形的上底为底，在里面画一个最大的三角形，这个三角形的面积是多少平方分米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<result>18</result>