X²-2XY+Y²-2X+2Y+1=0
(X-Y)²-2(X-Y)+1=0
(X-Y-1)²=0
X-Y-1=0
X=Y+1
周长=2(X+Y)=18
X+Y=9
Y+1+Y=9
Y=4,X=5
XY=20
所以面积=20平方厘米