解：設(shè)?$AC = x，$?則?$CF = BC = 7 - x。$?
?$ $?因?yàn)?$S_{1}+S_{2} = 29，$?
所以?$x^2+(7 - x)^2=29。$?
?$ $?又因?yàn)?$x+(7 - x)=7，$?
所以?$[x+(7 - x)]^2=7^2，$?
即?$x^2+2x(7 - x)+(7 - x)^2=49。$?
?$ $?則?$x(7 - x)=\frac {49 - 29}{2}=10。$?
?$ $?所以?$S_{陰影}=\frac {1}{2}AC·CF=\frac {1}{2}x(7 - x)=\frac {1}{2}×10 = 5。$?
