If a cylinder is cut into two halves along the diameter, the surface area increases by 320 square centimeters, what is the lateral area of the cylinder?
将一个圆柱沿直径切成两个半圆桂，表面积增加320平方厘米，圆柱的侧面积是多少．
<gadget id="calculator">320 / 2</gadget>
<output>160</output>

<gadget id="calculator">3.14 * 160</gadget>
<output>502.4</output>

<result>502.4</result>