AB:y=2x/3 +8/3
即2x-3y+8=0
下方,取2x-3y+8>=0
BC:y=-x+1
即x+y-1=0
上方,取x+y-1>=0
AC:Y=4x-4
即4x-y-4=0
上方,取4x-y-4<=0
所以,P(x,y)满足
2x-3y+8>=0且
x+y-1>=0且
4x-y-4<=0