It can, but not necessarily. The term quadrilateralrefers to any 4-sided polygon. This does not give you any information on the lengths or equalities of any sides or angles.
The subgroup of quadrilaterals that has equal opposite sides (because there are two sets of parallel sides) is a parallelogram.
rhombus. The rhombus is a quadrilateral with all sides equal in length. It is also a parallelogram, so opposite sides are parallel and equal in length, and opposite angles are equal.
Equal and parallel
A parallelogram.
They are equal and parallel.
It is not possible for a quadrilateral in Euclidean plane geometry to have no equal angles and still have its opposite sides parallel.It's possible for a quadrilateral to have no equal angles and two of its sides parallel (opposite ones, obviously; adjacent sides can't possibly be parallel). That would be a trapezoid.
A parallelogram has opposite sides and angles congruent which means of equal measure.
rhombus. The rhombus is a quadrilateral with all sides equal in length. It is also a parallelogram, so opposite sides are parallel and equal in length, and opposite angles are equal.
Parallogram
Equal and parallel
A parallelogram.
Rectangle Parallelogram
They are equal and parallel.
It is not possible for a quadrilateral in Euclidean plane geometry to have no equal angles and still have its opposite sides parallel.It's possible for a quadrilateral to have no equal angles and two of its sides parallel (opposite ones, obviously; adjacent sides can't possibly be parallel). That would be a trapezoid.
A general quadrilateral.
If a set of equal sides are adjacent, then the quadrilateral is a "kite" shape. If a set of equal sides are opposite, then the quadrilateral is a parallelogram.
rectangle
That quadrilateral is known as a 'parallelogram'.