Quadrilaterals ...

A parallelogram is a quadrilateral whose ...................... sides are parallel.

A parallelogram each of whose angle measures $$90^\circ$$ is

A quadrilateral whose all sides are equal and has four right angles is called a ____ .

Match the following.

If the diagonals of a quadrilateral bisect each other at right angle, then it is a __________.

Choose the correct statement.

If each pair of opposite sides of a quadrilateral are equal and parallel, then it is a ____________.

Choose the correct alternative : 
For every quadrilateral there are............element 

The angle of a quadrilateral are in the ratio $$3 : 4 : 5 : 6$$. The largest of them is:

If bisectors of $$\angle A$$ and $$\angle B$$ of a quadrilateral ABCD intersect each other at $$P$$, bisectors of $$\angle B$$ and $$\angle C$$ at $$Q$$, bisectors of $$\angle C$$ and $$\angle D$$ at $$R$$ and bisectors of $$\angle D$$ and $$\angle A$$ at $$S$$, then PQRS is a