The base of an isosceles triangle is 15 cm and the waist is 8 cm. What is its perimeter in cm?
一个等腰三角形的底是15厘米，腰是8厘米，它的周长是多少厘米．
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">16 + 15</gadget>
<output>31</output>

<result>31</result>