The upper base of the trapezoid is 8 meters, the lower base is 3 meters, and the height is twice the lower base. What is the area of the trapezoid in square meters?
梯形的上底是8米，下底是3米，高是下底的2倍，这个梯形的面积是多少平方米
<gadget id="calculator">8 + 3</gadget>
<output>11</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">11 * 3 * 1</gadget>
<output>33</output>

<result>33</result>