A polygon with 2n sides (n>1) can have opposite sides congruent.
A four-sided polygon with opposite sides parallel and all sides congruent is a square.
A polygon with five congruent sides is a pentagon.
It all depends on what kind of polygon it is. It may have no congruent sides or all congruent sides.
A square or a rhombus
A polygon with 2n sides (n>1) can have opposite sides congruent.
A four-sided polygon with opposite sides parallel and all sides congruent is a square.
Any polygon with an even number of sides can have opposite sides that are congruent and parallel.
A polygon with 2n sides (n>1) can have opposite angles congruent.
Any polygon with 2n sides (n integer) where opposite sides are parallel, will have its opposite angles congruent.
a trapezoid
A square
polygon
A rectangle is a quadrilateral with opposite sides parallel and congruent and four right angles. If all four sides are congruent, it is a square.
A rectangle is a quadrilateral with opposite sides parallel and congruent and four right angles. If all four sides are congruent, it is a square.
A polygon with five congruent sides is a pentagon.
A regular polygon is a polygon with congruent sides and interior angles.