Given:
ABCD is a quadrilateral
AC = 12, DE = 4 and FB = 5
To find:
The area of the polygon.
Solution:
AC bisects the quadrilateral into two triangles.
Area of triangle:

<u>Area of triangle DAC:</u>



Area of triangle DAC = 24 square units.
<u>Area of triangle BAC:</u>



Area of triangle BAC = 30 square units.
Area of polygon = Area of triangle DAC + Area of triangle BAC
= 24 square units + 30 square units
= 54 square units
The area of the polygon is 54 square units.