The figure below shows a parallelogram ABCD with perpendicular diagonals AC and BD.

If it is given that angle DAB is 80°, which statement is sufficient to guarantee that the parallelogram is a rhombus with all sides equal?

Question

The figure below shows a parallelogram ABCD with perpendicular diagonals AC and BD. 
 

 
If it is given that angle DAB is 80°, which statement is sufficient to guarantee that the parallelogram is a rhombus with all sides equal?

anonymous · Answer

Angle CAB is 40°, and angle DBA is 50°.
		Angle CAB is 50°, and angle DBA is 60°.
		Angle DBA is 40°.
		Angle CAB is 60°.

anonymous · Answer

attachment

anonymous · Answer

@AccessDenied  here it is ^^

anonymous · Answer

now when they say DAB is 80 degrees do they mean angle A or what?

accessdenied · Answer

|dw:1338659650776:dw|
That entire angle.

anonymous · Answer

ah k

accessdenied · Answer

I am thinking this deals with the idea that the diagonals should bisect their respective angles... so I believe we can assume this is true for it to be a rhombus:
|dw:1338659975193:dw|