There are two semicircular lawns in the street park, and their perimeters are both 128.5m. What is the total area of the lawn?
街心公园有两块半圆形的草坪，它们的周长都是128.5m．这块草坪的总面积是多少？
<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">25 ** 2</gadget>
<output>625</output>

<gadget id="calculator">3.14 * 625</gadget>
<output>1_962.5</output>

<result>1_962.5</result>