The height of a trapezoid is 7 cm, the product of its upper base is 78.4, and the product of its lower base is 178.4, then what is the area of this trapezoid in square centimeters?
一个梯形的高为7厘米，它与上底的乘积是78.4，与下底的乘积是178.4，那么这个梯形的面积是多少平方厘米．
<gadget id="calculator">78.4 + 178.4</gadget>
<output>256.8</output>

<gadget id="calculator">256.8 / 2</gadget>
<output>128.4</output>

<result>128.4</result>