quadrilaterals

The sides and angles of a rectangle: Opposite sides of a rectangle are the same length (congruent). The angles of a rectangle are all congruent (the same size and measure.) Remember that a 90 degree angle is  called a "right angle."  So, a rectangle has four right angles. Opposite angles of a rectangle are congruent.Opposite sides of a rectangle are parallel. The sides and angles of a square: The sides of a square are all congruent (the same length.) The angles of a square are all congruent (the same size and measure.) Remember that a 90 degree angle is  called a "right angle."  So, a square has four right angles. Opposite angles of a square are congruent.Opposite sides of a square are congruent.Opposite sides of a square are parallel. The sides and angles of a parallelogram: Opposite sides of a parallelogram are the same length (congruent). Opposite angles of a parallelogram are the same size/measure (congruent.) Opposite sides of a parallelogram are parallel... Uh... You think that's where it got it's name?  Other properties of the angles of a parallelogram: Adjacent sides (ones next to each other) of a parallelogram are supplementary.  This means that their measures add up to 180 degrees.   The sides and angles of a trapezoid: The bases (top and bottom) of a trapezoid are parallel. That's it.  No sides needs to be congruent and no angles need to be congruent.  Nothing special happens with the diagonals.