The cross-section of a part produced by a factory is a circle with a radius of 8 cm. Find its cross-sectional area.
工厂生产的一种零件的横截面是圆，半径是8厘米，求它的横截面积．
<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">3.14 * 64</gadget>
<output>200.96</output>

<result>200.96</result>