0 1 12 3456789

:; & lt=

1.c2

. /0 12 34 2.3 4 5

& gt？ & lt@

6 1

d 62 15063∶S△AHC = 14ac 2，S△CFB= 14BC2，S△A

BE= 14

AB2

,∴s78= 14ac2+ 14bc2+ 14ab2

=

14×2 AB2

= 12AB2=92

. Accelerated business collection and delivery system (adopted by the United States post office)

6 9△ABC:，； & ltAB= 10，BC=8，= & gt2AC，= & gt2