Calculate the area of a quadrilateral from the the lengths of the four sides and the sum of opposite angles using the formula.
Enter the lengths a, b, c, and d of the four sides and the sum of diagonals A+B, and click the "Calculate Area of Quadrilateral" button. Calculates and displays the area of a rectangle from the length of four sides and the sum of opposite angles.
![Area of quadrilateral(The four sides and the sum of opposite angles)](/img/area_en/quadrangle_four_side_angle.png)
![Formula of the area of the quadrangle from the sum of the four sides and the sum of opposite angles](/img/area_en/quadrangle_four_side_angle1.jpg)
![Bretschneider's formula](/img/area_en/quadrangle_four_side_angle2.jpg)
Area of quadrilateral with side a in 3, side b in 4, side c in 5, side d in 6, sum of opposite angles A+B in 180
Area S: 18.97366596101