# Finding the area of a quadrilateral

I have a quadrilateral whose four sides are given

2341276, 34374833, 18278172, 17267343 units.

How can I find out its area? What would be the area?

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Unlike a triangle, a quadrilateral is not uniquely defined by its side lengths. For example, if all sides are of unit length, it could be anything from a square with unit area to a very skinny rhombus with area close to zero. You need more information to determine the area, such as the angle between the diagonals, $\theta$ in PEV's answer. –  Rahul Jan 25 '11 at 14:16

Have you seen this(mathworld article)? In particular, the area of a planar quadrilateral is given by $\frac{1}{4}(b^2+d^2-a^2-c^2) \tan \theta$ where $a,b,c$ and $d$ are the side lengths.

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Isn't that only for convex quadrilaterals? –  Aryabhata Jan 25 '11 at 18:52
Use the Brahmagupta Formula, $A = \sqrt{(s-a)(s-b)(s-c)(s-d)}$, where $a$, $b$, $c$ and $d$ are the lengths of the four sides of the quadrilateral, and $s =\frac{a + b + c + d}2$.