A cylindrical oil barrel is a square when its sides are expanded. It is known that the radius of the bottom of the oil barrel is 10 cm. What is the height of the oil barrel in centimeters?
一个圆柱形油桶，侧面展开是一个正方形，已知这个油桶的底面半径是10厘米，那么油桶的高是多少厘米．
<gadget id="calculator">3.14 * 10 * 2</gadget>
<output>62.8</output>

<result>62.8</result>