The perimeter of a triangle is 0.7 decimeters, and the length of two sides is 0.2 decimeters. What is the length of the other side? What kind of triangle is this?
一个三角形的周长是0.7分米，其中有两条边的长度都是0.2分米，还有一条边的长度是多少分米？这是一个什么样的三角形？
<gadget id="calculator">0.2 * 2</gadget>
<output>0.4</output>

<gadget id="calculator">0.7 - 0.4</gadget>
<output>0.3</output>

<result>0.3</result>