## CGAL::polygon_area_2

### Definition

The function polygon_area_2 computes the signed area of a polygon.

#include <CGAL/Polygon_2_algorithms.h>

template <class ForwardIterator, class Traits>
typename Traits::FT

polygon_area_2 ( | ForwardIterator first, ForwardIterator last, Traits traits)

Computes the signed area of the polygon defined by the range of points first ... last. The sign is positive for counterclockwise polygons, negative for clockwise polygons. If the polygon is not simple, the area is not well defined.

### Requirements

1. Traits is a model of the concept PolygonTraits_2 . Only the following members of this traits class are used:
   - Compute_area_2 : Computes the signed area of the oriented triangle defined by 3 Point_2 passed as arguments.
   - FT
   - compute_area_2_object
2. ForwardIterator::value_type should be Traits::Point_2,

### See Also

PolygonTraits_2
CGAL::orientation_2
CGAL::Polygon_2<PolygonTraits_2, Container>