A square tablecloth is spread on a circular dining table with a diameter of 2 meters and a height of 1 meter. The four corners of the tablecloth just touch the ground. What is the area of the tablecloth in square meters?
直径2米、高1米的圆形餐桌上，铺了一块正方形台布，台布的四个角正好触到地面，这块台布的面积是多少平方米．
<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>