The perimeter of a triangle is 72 cm, the length of side a is 36 cm, and the length of side b is 18 cm. What is the length of side c in cm? What kind of triangle is this?
一个三角形的周长是72厘米，其中a边长是36厘米，b边长是18厘米，求c边长是多少厘米？这是一个什么三角形？
<gadget id="calculator">72 - 36 - 18</gadget>
<output>18</output>

<result>18</result>