The length of the hour hand of a clock is 5 cm. From 6 o'clock to 9 o'clock, what is the area swept by the hour hand?
一个时钟时针长5cm，它从6点到9点，时针扫过的面积是多少？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">25 / 4</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">3.14 * (25/4)</gadget>
<output>19.625</output>

<result>19.625</result>