Firstly, sorry if this question is too basic for this community but seriously I couldn't find any answer. Does it mean the multiplication of the in-plane lattice constants? For example, lets say following geometry file belongs the graphene.

C: Graphite Lattice
1.0
 +2.4410462393  +0.0000000000  +0.0000000000 
 -1.2205231197  +2.1140080551  +0.0000000000 
 +0.0000000000  +0.0000000000 +10.0000000000 
  2
Cartesian
 +0.0000000000  +0.0000000000  +0.0000000000 
 +0.0000000000  +1.4093387034  +0.0000000000 

So its formula unit surface area is: $2.4410462393*2.4410462393 = 5.958706742400672$. Am I right? If I'm wrong I'd be very appreciated for the correct logic.