Properties of Parallelograms The properties of the parallelogram
are simply those things that are true about it. These properties
concern its sides, angles, and diagonals. The parallelogram has
the following properties: Opposite sides are parallel by
definition. Opposite sides are congruent. Opposite angles are
congruent. Consecutive angles are supplementary. The diagonals
bisect each other. If you just look at a parallelogram, the
things that look true (namely, the things on this list) are true
and are thus properties, and the things that don’t look like
they’re true aren’t properties. If you draw a picture to help
you figure out a quadrilateral’s properties, make your sketch as
general as possible. For instance, as you sketch your
parallelogram, make sure it’s not almost a rhombus (with four
sides that are almost congruent) or almost a rectangle (with
four angles close to right angles). If your parallelogram sketch
is close to, say, a rectangle, something that’s true for
rectangles but not true for all para