# Calculating the area of any quadrilateral

Every quadrilateral is a polygon with four sides of any length connected together at the corners. The method of calculation for quadrilaterals is triangulation, which requires you to know the lengths of one of the two diagonals.

Through this formula, it's possible to find out the area of any quadrilateral, no matter if it's a parallelogram, rhombus, trapezoid – in short, every 4-sided surface expect a crossed quadrilateral.

### Triangulation calculation method

* Be careful to respect the order of the sides and use the diagonal 'ab' as shown on the drawing, otherwise you may get a wrong result.

Units:
Side a:
Side b:
diagonal ab:
Side c:
Side d:
Decimal places:
Units angles:
 Surface: 0,87 m2 Perimeter: 4,00 m Quadrilateral angles: (alfa) α : 60,00 ° (beta) β : 120,00 ° (gama) γ : 60,00 ° (delta) δ : 120,00 °

## The Angles of a Quadrilateral

The calculation is done as follows: find the sum of the squares of the two adjacent sides of the angle, which is then subtracted from the square of the opposite diagonal. Then, divide the result of this "addition/subtraction" by the product of the two adjacent sides times two. Finally, you calculate the arccosine of the above result. What a cinch! Now for those who need it, you can find aspirin, Tylenol or other headache medicine at your nearest drug store…