Question

pls tell formula for finding area of quadrilateral..........pls pls pls

Answer 1

to find the area of a non regular quadrilateral you can divide it into some triangle and using heron formula of 1/2bh find their area then sum up all the area of triangles

Answer 2

You can use Heron's formula (popularly known as Hero's formula) for triangles after splitting the quadrilateral into two triangles along any one diagonal. Just sum it up. Or if you know
the coordinates you could use the vector cross product for each triangle.
Another method: Brahmagupta (Indian mathematician, b.598, died between 660 and 670 AD) has given the formula to calculate the area of a quadrilateral as [(s-a)(s-b)(s-c)(s-d)]^0.5 where s = [a+b+c+d]/2. Here you do not need the lengths of the diagonals.