The diameter of a circular aquaculture farm is 50 meters. After the expansion, the radius increased by 5 meters. How many square meters did the area of the aquaculture farm increase after the expansion?
一个圆形水产养殖场的直径是50米．扩建后半径增加了5米，扩建后水产养殖场的面积增加了多少平方米？
<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">25 + 5</gadget>
<output>30</output>

<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

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

<gadget id="calculator">900 - 625</gadget>
<output>275</output>

<gadget id="calculator">3.14 * 275</gadget>
<output>863.5</output>

<result>863.5</result>