The radius of the base of a cylinder is 1 decimeter, and its sides are expanded to form a square. What is the height of the cylinder?
一个圆柱的底面半径是1分米，把它的侧面展开得到一个正方形，这个圆柱的高是多少．
<gadget id="calculator">2 * 3.14 * 1</gadget>
<output>6.28</output>

<result>6.28</result>