The diameter of the mouth of a circular water tank is 45 cm. To make a water tank head whose diameter is 5 cm longer than the diameter of the water tank mouth, what is the area of the water tank head in square centimeters?
一个圆形水缸口的直径是45cm，要做一个直径比水缸口直径长5cm的水缸盖，这个水缸盖的面积是多少平方厘米？
<gadget id="calculator">45 + 5</gadget>
<output>50</output>

<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>