Given that the two side lengths of an isosceles triangle are 8cm and 4cm respectively, what is the perimeter of this isosceles triangle in cm?
已知一个等腰三角形的两条边长分别是8cm和4cm，这个等腰三角形的周长是多少cm．
<gadget id="calculator">4 + 4 + 4 + 4 + 4</gadget>
<output>20</output>

<result>20</result>