∴AE=AB= 10,BF=EF
AC = 6
According to Pythagorean Theorem CE=8
∴DE=2
Let DF=x
Then EF=BF=6-x
∴(6-x)? =2? +x?
The solution is x=8/3.
∴△△ the area of def = 1/2*2*8/3=8/3cm?