Geometry

I believe the rhombus is a square for main reasons. 

For one thing, the opposite angles of a rhombus are 90 degrees, so we have two 90 degree angles.  

The adjacent angle also should be 90 degrees, so all 4 angles are 90 degrees. 

Therefore, we just have a square. 

We have $12*12=144$

So the area is 144. 

Thanks! :)

A rhombus with an angle of $90^\circ$ is the same as a square. Since the sides of a rhombus are all of equal length and the opposing angles are equal. If one of the angles are $90^\circ$then all of the angles are $90^\circ$. Which means the area is $12^2 = 144$