A trapezoid has an upper base of 6 cm, a lower base of 8 cm, and a height half of the upper base. What is its area in square centimeters?
一个梯形，上底是6厘米，下底是8厘米，高是上底的一半，它的面积是多少平方厘米．
<gadget id="calculator">6 + 8</gadget>
<output>14</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">14 * (3/2)</gadget>
<output>21</output>

<result>21</result>