The perimeter of a triangle is 82.8 centimeters, the length of side a is 35.2 centimeters, and the length of side b is 28.8 centimeters. Find the length of side c in centimeters? What kind of triangle is this?
一个三角形的周长是82.8厘米，其中边长a是35.2厘米，边长b是28.8厘米，求边长c多少厘米？这是一个什么三角形？
<gadget id="calculator">82.8 - 35.2 - 28.8</gadget>
<output>18.8</output>

<result>18.8</result>