According to the venn diagram what type of parallelogram is both a rectangle and a rhombus

According to the properties of a parallelogram.

Its opposite angles are equal and its opposite sides are also equal.

Now for a parallelogram to be a rectangle,

All its angles must be 90°.

But we also want the parallelogram to be a rhombus, which means all its sides must be equal.

Now any rectangle whose all sides are equal becomes a square.

And so parallelogram which is both a rectangle and a rhombus is a SQUARE.