the soluttion is extremely lengthy,i'll tell u  the method

 

find the point of intersection of the diagonals "O "

 

call this  (x1,y1)

 

using the formula

 

x - x1/cos(theta) = y - y1/sin(theta)  =  r

find the co-ordinates of A and C where   r  = 2 (as the point O bisects AC )

 

then assume co-ordiantes of B  as (x0,y0)

 

 u can get y0 is terms of  x0 as B lies on the other diagonal

 

now get the equation of AB .

from this get the distance of point C from AB ,this is the heigth

now use  area = base x  heigth

u will get co-ordinates of B and hence D .

 

now find BD,AB,BC 

 

phew !!!!!!