If the two sides of an isosceles triangle are 3 decimeters and 7 decimeters long, what is the length of the third side?
一个等腰三角形的两条边分别长3分米和7分米，第三条边长多少分米．
<gadget id="calculator">7 + 7 + 3</gadget>
<output>17</output>

<result>17</result>