Squares are quadrilaterals with 4 congruent sides and 4 right angles, and they also have two sets of parallel sides. Parallelograms are quadrilaterals with two sets of parallel sides. Since squares must be quadrilaterals with two sets of parallel sides, then all squares are parallelograms.
A rectangle has all the properties of a parallelogram, plus the following: The diagonals are congruent.
Squares are quadrilaterals with 4 congruent sides and 4 right angles, and they also have two sets of parallel sides.
Parallelograms are quadrilaterals with two sets of parallel sides. Since squares must be quadrilaterals with two sets of parallel sides, then all squares are parallelograms. This is always true. (actually is true)
