The area of a trapezoid is 19.11 square centimeters. It is known that its upper base is 6.3 cm, lower base is 2.8 cm, and its height is in cm.
一个梯形的面积是19.11平方厘米，已知它的上底是6.3厘米，下底2.8厘米，高是多少厘米．
<gadget id="calculator">6.3 + 2.8</gadget>
<output>9.1</output>

<gadget id="calculator">2 / 9.1</gadget>
<output>0.21978</output>

<gadget id="calculator">19.11 * 0.21978</gadget>
<output>4.199996</output>

<result>4.199996</result>