Sol. Join BD.
We know, area of ∆ABD
Here, we have x1 = 0, y1 = 0
x2 = 6, y2 = 0
and x3 = 0, y3 = 3
Now, area of ∆ABD
We know that, area of ∆BCD
Here, we have x1 = 6, y1 = 0
x2 = 4, y2 = 3
and x3 = 0, y3 = 3
Now. area of ∆BCD
Hence, the area of quadrilateral ABCD
= area (∆ABD) + area (∆BCD)
= (9 + 6) sq. units = 15 sq. units.