In 3-dimensional geometry, for a finite planar surface of scalar area
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=1770)
and
unit normal ![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=2796)
, the vector area
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=2432)
is defined as the unit normal scaled by the area:
For an
orientable surface S composed of a set
![](http://info.babylon.com/onlinebox.cgi?rt=GetFile&uri=!!ARV6FUJ2JP&type=0&index=3310)
of flat
facet areas, the vector area of the surface is given by