- The second group of quadrilaterals has exactly one pair of parallel
sides and are called trapezoids. If the non-parallel opposite sides
are congruent, it is called an isosceles trapezoid, as pictured in the
following illustration. - The third group of quadrilaterals is parallelograms, which have
two pairs of parallel sides. A parallelogram is typically drawn as
follows, but as we will explore, there are three more specific ways
that we can classify parallelograms.- A rectangleis a parallelogram that has four right angles.
- A squareis a parallelogram that has four right angles and four
equal sides. (All squares are rectangles, but not all rectangles
are squares!) - A rhombusis any quadrilateral that has four equal sides. All
rhombuses are parallelograms. (All squares are rhombuses, but
not all rhombuses are squares!)
Each of the special types of quadrilaterals listed above has a list of unique
characteristics that pertain to the relationship between the quadrilateral’s con-
secutive angles, opposite angles, and/or diagonals. Read on for a compre-
hensive list of the characteristics that define each group of quadrilaterals.
501 Geometry Questions