The trapezoidal section (left-side) can be seen as

whence determining the Area for this left-sided portion ( Al ) of the property proceeds as follows:
Al = |
12(300 m + 400 m) × 500 m |
= |
12(700 m) × 500 m |
= |
350 m × 500 m |
= |
175,000 m² |
The right triangle section (right-side) appears as,

and finding the Area of this second region ( Ar ) can be carried out as follows:
Ar = |
12(300 m) × 400 m |
= | 150 m × 400 m |
|
|
Armed with the measures for the Areas from both sections of the property, we see that...

The total Area of the entire property is nothing more than the sum of Al
& Ar ...
A = |
175,000 m² + 60,000 m² |
= |
235,000 m² |
All that remains to be done is to convert units, from
square meters ( m² )
to hectares
( ha), which may be achieved by using our standard operating procedure (SOP):
A = |
235,000 m² |
× |
1 ha |
|
10,000 m² |
= |
 |
|
= |
235 × 1 ha |
|
10 |
= |
|
|