The upper base of a right-angled trapezoid is 4 cm, the height is 2 cm, and the lower base is 5 cm. Cut a rectangle out of it. What is the maximum area of the rectangle in square centimeters?
一个直角梯形的上底是4厘米，高是2厘米，下底是5厘米，用它剪一个长方形，长方形的面积最大是多少平方厘米．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>