An isosceles trapezoid, the upper and lower bases are 7 cm and 12 cm respectively, and the length of one side is 8 cm. What is the perimeter of this isosceles trapezoid?
一个等腰梯形，上底和下底分别是7厘米和12厘米，一条腰长是8厘米，这个等腰梯形的周长是多少．
<gadget id="calculator">8 + 8 + 7 + 12</gadget>
<output>35</output>

<result>35</result>