There are two small sticks, 7cm and 15cm long respectively. If a small stick is combined to form an isosceles triangle as large as possible, what is the length of the resulting small stick in cm?
有两根小棒，分别长7cm和15cm，如果配一根小棒来围成一个尽可能大的等腰三角形，配成的这根小棒的长度应该是多少cm．
<result>15</result>