Find the area of this irregular polygon.

Answer:
970m^{2}
Step-by-step explanation:
This polygon can be divided in two figures: one is a triangle, an the other one is a square.
We'll begin calculating the triangle's area, using the following formula:
[tex]At= \frac{b.h}{2}[/tex]
Where:
[tex]H= height = 30 m[/tex]
[tex]B = 9 m + 9 m + 20 m = 38 m[/tex]
As you can see, I added both sides of the triangle that measure 9 m and also the lenght of the square that measures 20 m! This added up is what the base of the triangle measures on total.
[tex]At= \frac{38 m .30 m}{2}[/tex]
[tex]At= \frac{1140 m^{2} }{2}[/tex]
[tex]At= 570 m^{2} [/tex]
Now we are going to calculate the square's area, that is much more simple:
[tex]As= L^{2} [/tex]
Where:
[tex]L=20 m [/tex]
[tex]As= (20 m)^{2} = 400m^{2} [/tex]
To know the whole figure's area, we add up both areas:
[tex]A = At+As = 570m^{2} +400m^{2}=970m^{2} [/tex]