If the lengths of the two sides of a triangle are 5 cm and 8 cm, what is the impossible length of the third side of the triangle?
如果一个三角形的两条边长分别是5厘米和8厘米，则这个三角形的第三条边长不可能是多少厘米．
<gadget id="calculator">8 + 5</gadget>
<output>13</output>

<result>13</result>