5.6 Proving That a Quadrilateral is a Parallelogram Objective: After studying this section, you will...
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Transcript of 5.6 Proving That a Quadrilateral is a Parallelogram Objective: After studying this section, you will...
5.6 Proving That a Quadrilateral is a
ParallelogramObjective:
After studying this section, you will be able to prove that a quadrilateral is a
parallelogram.
Methods to prove quadrilateral ABCD is a parallelogram
1. If both pairs of opposite sides of a quadrilateral are parallel, then the quadrilateral is a parallelogram (reverse of the definition).
A B
D C
2. If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram (converse of a property).
3. If one pair of opposite sides of a quadrilateral are both parallel and congruent, then the quadrilateral is a parallelogram.
4. If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram (converse of a property).
5. If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram (converse of a property).
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Given: ACDF is a parallelogram
Prove: FBCE is a parallelogram
C
E
A
DF
B
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AFB ECD
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Given:
C K
A
R
B
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AC BK
C K
is isosceles, with base CAR CR
Prove: BARK is a parallelogram
Given: Quadrilateral QUAD with angles as shown
Show that QUAD is a parallelogram UA
QD
52x
10x 23 5x x x
3 23 15x x
Given: NRTW is a parallelogram
Prove: XPSV is a parallelogram
R
T
N
W V
S
P
X
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NX TS
WV PR
Summary
Using one of the methods to prove quadrilaterals are parallelograms, create your own problem and show how it is a parallelogram.
Homework: worksheet