A square's opposite sides are parallel and all the sides are congruent.
Trapezoid.
There is no specific name for such an irregular quadrilateral.
A square
No, you need both pairs of opposite sides to be congruent (i.e. the same size) to be a parallelogram.
A kite
This quadrilateral is a trapezoid. In a trapezoid, one pair of opposite sides is parallel, and one pair of opposite sides is congruent. The other two sides are not parallel or congruent.
The Opposite Sides Parallel and Congruent Theorem states that if a quadrilateral has a pair of opposite sides that are parallel and congruent, then the quadrilateral is a parallelogram.
A quadrilateral with both pairs of opposite sides congruent is a parallelogram.
A parallelogram has two pairs of congruent sides, and the opposite sides are congruent.
No. The congruent sides need not be parallel.
Then, the opposite sides are congruent.
parellelagram
always
A square's opposite sides are parallel and all the sides are congruent.
If a quadrilateral has two pairs of opposite congruent sides, then the quadrilateral is a parallelogram.
Diamond