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Transcript
Names: __________________________________________
2
PARALLELOGRAMS PROOFS UNSCRAMBLE
Directions: Cut out the steps of the proof and arrange them (and glue them) logically to prove that the
shape is parallelogram. Mark the quadrilateral with the information in the proof as you go.
Proof #1: If opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram.
Μ…Μ…Μ…Μ… and 𝐢𝐷
Μ…Μ…Μ…Μ… are congruent and that 𝐴𝐷
Μ…Μ…Μ…Μ… and 𝐡𝐢
Μ…Μ…Μ…Μ…
We are given that 𝐴𝐡
are congruent.
Μ…Μ…Μ…Μ… and 𝐷𝐡
Μ…Μ…Μ…Μ… are congruent using the reflexive property because
𝐡𝐷
they are the same line.
So, triangle ABC is congruent to triangle CDB by the Side-Side-Side
congruence.
This means that angle ABC and angle CDB are congruent because
corresponding parts of congruent triangles are congruent.
Then we can see that ∠𝐴𝐡𝐢 and ∠𝐢𝐷𝐡 are alternate interior
angles formed by the lines Μ…Μ…Μ…Μ…
𝐴𝐡 and Μ…Μ…Μ…Μ…
𝐢𝐷 with the transversal Μ…Μ…Μ…Μ…
𝐡𝐷.
Because they are congruent alternate interior angles, we know
Μ…Μ…Μ…Μ… and 𝐢𝐷
Μ…Μ…Μ…Μ… are parallel.
that 𝐴𝐡
Similarly, angle BDA is congruent to angle DBC since corresponding
parts of congruent triangles are congruent.
Then we can see that ∠𝐡𝐷𝐴 and ∠𝐷𝐡𝐢 are alternate interior
angles formed by the lines Μ…Μ…Μ…Μ…
𝐴𝐢 and Μ…Μ…Μ…Μ…
𝐡𝐷 with the transversal Μ…Μ…Μ…Μ…
𝐡𝐢 .
Because they are congruent alternate interior angles, we know
that Μ…Μ…Μ…Μ…
𝐴𝐷 and Μ…Μ…Μ…Μ…
𝐡𝐢 are parallel.
Since we have two sets of parallel sides that form quadrilateral
ABCD, we know that ABCD is a parallelogram.
1 – Attempt at proof
unscramble is
incomplete.
2 – There are large
logical errors in the proof
or diagrams.
3 – There are small
errors in the proof or
diagrams.
4 – Proof is unscrambled
correctly and most
diagrams are marked
with correct information.
5 – Proof is unscrambled
correctly and all
diagrams are marked
with correct information.
Names: __________________________________________
2
PARALLELOGRAMS PROOFS UNSCRAMBLE
Directions: Cut out the steps of the proof and arrange them (and glue them) logically to prove that the
shape is parallelogram. Mark the quadrilateral with the information in the proof as you go.
Proof #2: If one pair of opposite sides of a quadrilateral is congruent and parallel, then the
quadrilateral is a parallelogram.
We are given that Μ…Μ…Μ…Μ…
𝐴𝐡 and Μ…Μ…Μ…Μ…
𝐷𝐢 are parallel. We are also given that
Μ…Μ…Μ…Μ… is congruent to 𝐷𝐢
Μ…Μ…Μ…Μ… .
𝐴𝐡
Μ…Μ…Μ…Μ… and 𝐷𝐢
Μ…Μ…Μ…Μ… are parallel, we
Μ…Μ…Μ…Μ…, since 𝐴𝐡
If we draw in the diagonal 𝐡𝐷
form congruent alternate interior angles ∠𝐴𝐡𝐷 and ∠𝐢𝐷𝐡.
Μ…Μ…Μ…Μ…
𝐡𝐷 is congruent to Μ…Μ…Μ…Μ…
𝐷𝐡 since they are the same line using the
reflexive property.
Then, we can use the Side-Angle-Side triangle congruence
theorem to show that Δ𝐴𝐡𝐷 is congruent to Δ𝐢𝐷𝐡.
Then we also know that ∠𝐢𝐡𝐷 is congruent to ∠𝐴𝐷𝐡, since
corresponding parts of congruent triangles are congruent.
But ∠𝐢𝐡𝐷 and ∠𝐴𝐷𝐡 are also alternate interior angles formed by
the lines Μ…Μ…Μ…Μ…
𝐴𝐷 and Μ…Μ…Μ…Μ…
𝐡𝐢 with the transversal Μ…Μ…Μ…Μ…
𝐡𝐷.
Since they are congruent alternate interior angles, we know that
Μ…Μ…Μ…Μ…
𝐴𝐷 and Μ…Μ…Μ…Μ…
𝐡𝐢 are parallel.
Since we have two sets of parallel sides that form quadrilateral
ABCD, we know that ABCD is a parallelogram.
1 – Attempt at proof
unscramble is
incomplete.
2 – There are large
logical errors in the proof
or diagrams.
3 – There are small
errors in the proof or
diagrams.
4 – Proof is unscrambled
correctly and most
diagrams are marked
with correct information.
5 – Proof is unscrambled
correctly and all
diagrams are marked
with correct information.
Names: __________________________________________
2
PARALLELOGRAMS PROOFS UNSCRAMBLE
Directions: Cut out the steps of the proof and arrange them (and glue them) logically to prove that the
shape is parallelogram. Mark the quadrilateral with the information in the proof as you go.
Proof #3: If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram.
Μ…Μ…Μ…Μ… and 𝑂𝐢
Μ…Μ…Μ…Μ… are congruent and that 𝐷𝑂
Μ…Μ…Μ…Μ… and 𝑂𝐡
Μ…Μ…Μ…Μ…
We are given that 𝐴𝑂
Μ…Μ…Μ…Μ…
Μ…Μ…Μ…Μ…
are congruent. First, we will prove that 𝐡𝐢 and 𝐴𝐷 are parallel.
Because βˆ π΄π‘‚π· and βˆ πΆπ‘‚π΅ are vertical angles, we know that they
are congruent.
So Δ𝐴𝑂𝐷 and Δ𝐢𝑂𝐡 are congruent by the Side-Angle-Side triangle
congruence theorem.
Because of this, we know that βˆ π‘‚π·π΄ and βˆ π‘‚π΅πΆ are congruent
because corresponding parts of congruent triangles are congruent.
But βˆ π‘‚π·π΄ and βˆ π‘‚π΅πΆ are also alternate interior angles formed by
Μ…Μ…Μ…Μ… and 𝐴𝐷
Μ…Μ…Μ…Μ… and the transversal 𝐡𝐷
Μ…Μ…Μ…Μ….
𝐡𝐢
Since they are congruent alternate interior angles, we know that
Μ…Μ…Μ…Μ… and 𝐴𝐷
Μ…Μ…Μ…Μ… are parallel.
𝐡𝐢
We can apply the same logic to prove that Μ…Μ…Μ…Μ…
𝐴𝐡 and Μ…Μ…Μ…Μ…
𝐢𝐷 are parallel.
βˆ π΄π‘‚π΅ and βˆ πΆπ‘‚π· are congruent because they are vertical angles.
Δ𝐴𝑂𝐡 and Δ𝐴𝑂𝐡 are congruent triangles because of the SideAngle-Side congruence theorem.
βˆ π΅π΄π‘‚ and βˆ π·πΆπ‘‚ are congruent because corresponding parts of
congruent triangles are congruent.
βˆ π΅π΄π‘‚ and βˆ π·πΆπ‘‚ are also alternate interior angles formed by Μ…Μ…Μ…Μ…
𝐴𝐡
Μ…Μ…Μ…Μ… and the transversal 𝐴𝐢
Μ…Μ…Μ…Μ… .
and 𝐢𝐷
Since they are congruent alternate interior angles, we know that
Μ…Μ…Μ…Μ…
𝐴𝐡 and Μ…Μ…Μ…Μ…
𝐢𝐷 are parallel.
Since we have two sets of parallel sides that form quadrilateral
ABCD, we know that ABCD is a parallelogram.
1 – Attempt at proof
unscramble is
incomplete.
2 – There are large
logical errors in the proof
or diagrams.
3 – There are small
errors in the proof or
diagrams.
4 – Proof is unscrambled
correctly and most
diagrams are marked
with correct information.
5 – Proof is unscrambled
correctly and all
diagrams are marked
with correct information.
Names: __________________________________________
2
PARALLELOGRAMS PROOFS UNSCRAMBLE
Directions: Cut out the steps of the proof and arrange them (and glue them) logically to prove that the
shape is parallelogram. Mark the quadrilateral with the information in the proof as you go.
Proof #4: If one angle is supplementary to both consecutive angles in a quadrilateral, the quadrilateral
is a parallelogram.
We are given that angle A and angle B are supplementary.
We are also given that angle A and angle D are supplementary.
Because angle A and angle B are same side interior angles formed
by Μ…Μ…Μ…Μ…
𝐴𝐷 and Μ…Μ…Μ…Μ…
𝐡𝐢 with the transversal Μ…Μ…Μ…Μ…
𝐴𝐡 that are supplementary, we
Μ…Μ…Μ…Μ… and 𝐡𝐢
Μ…Μ…Μ…Μ… are parallel.
know that 𝐴𝐷
Because angle A and angle D are same side interior angles formed
by Μ…Μ…Μ…Μ…
𝐴𝐡 and Μ…Μ…Μ…Μ…
𝐷𝐢 and the transversal Μ…Μ…Μ…Μ…
𝐴𝐷 that are supplementary, we
Μ…Μ…Μ…Μ… and 𝐡𝐢
Μ…Μ…Μ…Μ… are parallel.
know that 𝐴𝐡
Μ…Μ…Μ…Μ… and 𝐡𝐢
Μ…Μ…Μ…Μ… are parallel and 𝐴𝐡
Μ…Μ…Μ…Μ… and 𝐡𝐢
Μ…Μ…Μ…Μ… are parallel, we
Because 𝐴𝐷
know that ABCD is a parallelogram, since it is formed by two pairs
of parallel sides.
1 – Attempt at proof
unscramble is
incomplete.
2 – There are large
logical errors in the proof
or diagrams.
3 – There are small
errors in the proof or
diagrams.
4 – Proof is unscrambled
correctly and most
diagrams are marked
with correct information.
5 – Proof is unscrambled
correctly and all
diagrams are marked
with correct information.