In a triangle, the lengths of the three sides are 13 cm, 21 cm and 19 cm respectively, what is the perimeter of the triangle in cm?
一个三角形，三条边的长度分别是13厘米、21厘米和19厘米，这个三角形的周长是多少厘米．
<gadget id="calculator">21 + 19 + 13</gadget>
<output>53</output>

<result>53</result>