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.
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
Trapezoid.
Parallelograms, rhombuses, squares, and rectangles are the quadrilaterals that have opposite congruent sides.