An isosceles triangle whose two sides are 3 cm and 7 cm respectively, what is the perimeter of this triangle?
一个等腰三角形，它的两条边分别是3厘米，7厘米，那么这个三角形的周长是多少．
<gadget id="calculator">7 + 7 + 3</gadget>
<output>17</output>

<result>17</result>