Geometry Help:

Determine if each biconditional statement is true, if false, give a counterexample.

-A figure is a quadrilateral if and only if it is a polygon.

Also I think I got this one, but if someone could help with it too, that would be appreciated.

- xy=0 if and only if x=0 or y=0

Question

Geometry Help:

Determine if each biconditional statement is true, if false, give a counterexample.

-A figure is a quadrilateral if and only if it is a polygon.

Also I think I got this one, but if someone could help with it too, that would be appreciated.

- xy=0 if and only if x=0 or y=0

anonymous · Answer

The first is false, |dw:1415257935719:dw| a polygon but not a quadrilateral, and since it's an if and only if, a polygon must imply a quadrilateral

anonymous · Answer

Well with the second part, x or y must be 0 for -xy = 0

Either or could be 0, but one of them has to be.