There are two small rods 2 cm and 4 cm long. To form an isosceles triangle, how many centimeters is the third stick.
有两根小棒分别长2厘米和4厘米．要围成一个等腰三角形，第三根小棒多少厘米．
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<result>4</result>