The diameter of the round dining table is 2 meters, the height is 1 meter, and the four corners of the square tablecloth spread on the table just touch the ground. Find the area of the square tablecloth.
圆形餐桌的直径为2米，高为1米，铺在桌面上的正方形桌布的四角恰好刚刚接触地面．求正方形桌布的面积．
<gadget id="calculator">2 + 1 + 1</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>