The upper base of a right-angled trapezoid is 4.5 meters, the lower base is 6.3 meters, and the height is 2.1 meters. What is the area of this right-angled trapezoid?
一个直角梯形的上底是4.5米，下底是6.3米，高是2.1米，这个直角梯形的面积是多少．
<gadget id="calculator">4.5 + 6.3</gadget>
<output>10.8</output>

<gadget id="calculator">2.1 / 2</gadget>
<output>1.05</output>

<gadget id="calculator">10.8 * 1.05</gadget>
<output>11.34</output>

<result>11.34</result>