There is a semicircular square with a perimeter of 205.6m, what is the area of the square?
有一个半圆形广场的周长是205.6m，求该广场的面积？
<gadget id="calculator">40 ** 2</gadget>
<output>1_600</output>

<gadget id="calculator">1_600 / 2</gadget>
<output>800</output>

<gadget id="calculator">3.14 * 800</gadget>
<output>2_512</output>

<result>2_512</result>