It is known that one base of a right-angled trapezoid is 6 cm. If the other base is extended by 2 cm, the right-angled trapezoid becomes a square. What is the area of the original right-angled trapezoid in square centimeters?
已知一个直角梯形的一条底是6厘米，如果将另一条底延长2厘米，该直角梯形就变成一个正方形，原直角梯形的面积是多少平方厘米．
<gadget id="calculator">6 - 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<result>30</result>