The length of the minute hand on the clock face is 5 cm. From 4 o'clock to 5 o'clock, what is the area swept by the minute hand in square centimeters?
钟面上分针长5厘米，从4时到5时，分针扫过的面积是多少平方厘米．
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>