Similarly,

∴△FMN∽△ABC

D and e are the midpoint of AB and AC respectively. According to the similarity ratio,

∴S= 1/9

(2) The D-crossing point is DH∨BE, and the AC-crossing point is H.

By substitution: FM/AB=2/9

△FMN∽△ABC from ( 1)

S=4/8 1

(3) the square of s =1(A+B+ 1)