Triangle : A triangle is a three-sided polygon.
The midsegment of a triangle is equal to 1/2 the base and is pararellel to the base.
The three midsegments of a triangle devide the triangle into four congruent triangles.
Rectangle : A quadrilateral with all angles as right angles.
The diagonals of rectangle are congruent.
Square : A rectangle with all congruent sides.
Kite : A quadrilateral with exactly two pairs of distinct congruent consecutive sides.
The diagonals of a kite are perpendicular.
The diagonal connecting the vertex angles of a kite is the perpendicular bisector of the other diagonal.
The nonvertex angles of a kite are congruent.
A diagonal bisects the vertex angles of a kite.
Trapezoid : A quadrilateral with exactly one pair of parallel sides.
Consecutive angeles between the bases of a trapezoid are supplementary.
An isosceles trapezoid is a trapezoid whose two non-parallel sides is the same length.
The base angles of an isoceles triangle are congruent.
The diagonals of an isosceles trapezoid are congruent.
The midsegment of a trapezoid is equal in length to the average of the two bases and is parallel to the base.
Parallelogram : A quadrilateral whose opposite sides are parallel.
The opposite sides of a parallelogram are congruent.
Consecutive angles in a parallelogram are supplementary.
Opposite angles in a parallelogram are congruent.
The diagonals of a parallelogram bisect each other.
Rhombus : A parallelogram with all four sides congruent.
The diagonals of a rhombus are perpendicular bisectors of each other.
The diagonals of a rhombus bisect the angles of the rhombus.
Here is a Venn Diagram to help catagorize the different Quadrilateral:
* An apothem is the perpendicular distance from the center of a polygon's circumscribed circle to one of it's sides.