heshamelaziry wrote:E, F, G, and H are the vertices of a polygon. Is polygon EFGH a square?

(1) EFGH is a parallelogram.

(2) The diagonals of EFGH are perpendicular bisectors of one another.

OA E

Please tell me the rules for this one. i.e, all squares are rectangles, but not all rectangles are squares

1. not all parallelograms are square but a square is a parallelogram so insuff

2. this means that it is a rhombus (all sides are equal) but you could have a diamond shape rhombus which is not a square hence insuff

1 and 2 doesnt tell you anything new since a rhombus is always a parallelogram anyway hence insuff.

to figure out that a shape is a square we need to know that all its sides are equal and has 4 right angles (i.e. is a rhombus and is a rectangle). Here we know the sides are equal but we dont know if the angles condition holds.

hope that helps.