How to find the area of a quadrilateral

a quadrilateral is a polygon with four 'sides' or edges and four vertices or corners. Sometimes, the term quadrangle is used, for analogy with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-sided) and so on. The word quadrilateral is made of the words quad and lateral. Quad means four and lateral means sides. The interior angles of a quadrilateral add up to 360 degrees of arc.Quadrilaterals are simple (not self-intersecting) or complex (self-intersecting). Simple quadrilaterals are either convex or concave.

Two identical isosceles triangles with side length 5 cm are joined at their bases with length 8 cm .What is the area of the quadrilateral.


a²+b²=c²

4²+b²=5²

16+b²=25

b²=25-16

b²=9

b=√9=3

Now by using area of triangle formula let's find the area of ABC ,which is
a part of the quadrilateral
Area of Δ ABC=1/2 (8)(3)

= 4*3=12 square units

Area of quadrilateral ABCD=12+12 =24 square units