No.
For any random quadrilateral, they are actually "never" congruent. The probability of the sides being so is infinitely less than the probability they will not be.
A square's opposite sides are parallel and all the sides are congruent.
square
Trapezoid.
There is no specific name for such an irregular quadrilateral.
No, you need both pairs of opposite sides to be congruent (i.e. the same size) to be a parallelogram.
always
It is a rectangle.
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
A square's opposite sides are parallel and all the sides are congruent.
square
A square, always, a rhombus, always, a parallelogram, always, and rectangles, always.
If a quadrilateral has two pairs of opposite congruent sides, then the quadrilateral is a parallelogram.