honors geometry section 4.6 (1) conditions for special quadrilaterals
TRANSCRIPT
Honors Geometry Section 4.6 (1)
Conditions for Special Quadrilaterals
In section 4.5, we answered questions such as “If a quadrilateral is a parallelogram,
what are its properties?” or “If a quadrilateral is a rhombus, what are its properties?” In this section we look to
reverse the process, and answer the question “What must we know about a
quadrilateral in order to say it is a parallelogram or a rectangle or a
whatever?”
What does it take to make a parallelogram?
State whether the following conjectures are true or false. If it is
false, draw a counterexample.
If one pair of opposite sides of a quadrilateral are congruent,
then the quadrilateral is a parallelogram.
If one pair of opposite sides of a quadrilateral are parallel,then the quadrilateral is a parallelogram.
If one pair of opposite sides of a quadrilateral are both parallel and
congruent, then the quadrilateral is a parallelogram.
If both pairs of opposite sides of a quadrilateral are parallel,then the quadrilateral is a parallelogram.
If both pairs of opposite sides of a quadrilateral are congruent, then
the quadrilateral is a parallelogram.
If the diagonals of a quadrilateral bisect each other, then the
quadrilateral is a parallelogram.
The last 4 statements will be our tests for determining if a
quadrilateral is a parallelogram.
If a quadrilateral does not satisfy one of these 4 tests, then we
cannot say that it is a parallelogram!
What does it take to make a rectangle?
State whether the following conjectures are true or false. If it is
false, draw a counterexample.
If one angle of a quadrilateral is a right angle, then the quadrilateral
is a rectangle.
If one angle of a parallelogram is a right angle, then the parallelogram
is a rectangle.
If the diagonals of a quadrilateral are congruent, then the
quadrilateral is a rectangle.
If the diagonals of a parallelogram are congruent, then the
parallelogram is a rectangle.
If the diagonals of a parallelogram are perpendicular , then the parallelogram is a rectangle.
Statements 2 and 4 will be our tests for determining if a
quadrilateral is a rectangle.
Notice that in both of those statements you must know that
the quadrilateral is a parallelogram before you can say that it is a
rectangle.
What does it take to make a rhombus?
State whether the following conjectures are true or false. If it is
false, draw a counterexample.
If one pair of adjacent sides of a quadrilateral are congruent, then
the quadrilateral is a rhombus.
If one pair of adjacent sides of a parallelogram are congruent, then
the parallelogram is a rhombus.
If the diagonals of a parallelogram are congruent, then the
parallelogram is a rhombus.
If the diagonals of a parallelogram are perpendicular then the parallelogram is a rhombus.
If the diagonals of a parallelogram bisect the angles of the parallelogram, then the
parallelogram is a rhombus.
Statements 2, 4 and 5will be our tests for determining if a
quadrilateral is a rhombus.
Notice that in each of these statements you must know that
the quadrilateral is a parallelogram before you can say that it is a
rhombus.
What does it take to make a square?
It must be a parallelogram, rectangle and rhombus.
Examples: Consider quad. OHMY with diagonals that intersect at point S. Determine if the given
information allows you to conclude that quad. OHMY is a
parallelogram, rectangle, rhombus or square. List all that apply.