The upper base of the trapezoid is 8 cm long, the lower base is 14 cm long, and the height is half of the upper base. What is the area of the trapezoid in square centimetres.
梯形的上底长8厘米，下底长14厘米，高是上底的一半．梯形的面积是多少平方厘米．
<gadget id="calculator">8 + 14</gadget>
<output>22</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">22 * 2</gadget>
<output>44</output>

<result>44</result>