Maximum Area of a Polygon with Vertices of a Polygon
Python 2, 172 bytes

-1 byte thanks to J843136028

bug fix thanks to Jonathan Frech



from itertools import*
def f(l,n,L=()):
 for p in combinations(l,n):
  r=0;j=-1
  for i in range(n):r+=(p[j][0]+p[i][0])*(p[j][1]-p[i][1]);j=i
  L+=abs(r/2.),
 print max(L)


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