The lateral expansion of a cylinder is a square, the diameter of the base is 4 decimeters, what is the height in decimeters
一个圆柱体的侧面展开是一个正方形，底面直径是4分米，高是多少分米
<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>