1) 根据圆弧和弦的关系，同一圆内，相等长度的弦所对应的弧也相等。
2) Since 连续四边长度为 3，其余长度为 2，设定该八边行为 ABCDEFGH where AB=BC=CD=DE=3, and EF=FG=GH=HA=2, connect CG.
3) From 1), 2) above, 可以推出 弧 AB=BC=CD=DE and 弧 EF=FG=GH=HA, therefore, 弧 CG = CD+DE+EF+FG = AB+BC+GH+HA=180 and 弧 DF=DE+EF=90.
4) Connect CF, DF and DG, 设 CF and DG 的交点为 P.
5) Since 弧 CG=180, therefore, CG 为直径, 角CDG=90, 角CFG=90.
6) Since 弧 DF=90, therefore 角DCG=角FCG=45.
7) From 5), 6), 角DPC=角FPG=45, therefore, DP=3, FP=2, CP=3sqrt(2) and PG=2sqrt(2).
8) Since C,D,F,G 共圆, 三角形 DFP 和 CGP 相似，therefore, CGP面积/DFP面积=(PG/PF)^2=2
9) Since PF=FG=EF=2,PD=CD=DE=3, and DF=DF, 三角形 DFP 和 DFE 全等.
10) From 8), 9), DEFP面积=CGP面积.
11) From 10), CDEFG面积=CDG面积+DEFP面积+PFG面积=CDG面积+CFG面积
12) CDG面积=CD*DG/2=3*(3+2sqrt(2))/2, CFG面积=2*(2+3sqrt(2))/2, therefore CDEFG面积=(13+12sqrt(2))/2
13) Since CDEFG=CBAHG, therefore 八边形面积=13+12sqrt(2).