There is a square grass field with a side length of 10 meters. A sheep is tied to each of two opposite vertices. The rope is 10 meters long. What is the area where the two sheep can eat grass?
有一块正方形草地，边长10米，一组相对的两个顶点上各系有一只羊，绳长10米，这两只羊都能吃到草的面积是多少？
<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3.14 * 100 * (1/2)</gadget>
<output>157</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">157 - 100</gadget>
<output>57</output>

<result>57</result>