12 multiple-choice questions, progressively harder.
In parallelogram ABCDABCDABCD, the side lengths in centimeters are given by
What is xxx?
Solution
Correct answer: C
The labeled sides are opposite.
Consecutive angles of a parallelogram measure (3x+8)∘(3x+8)^\circ(3x+8)∘ and (4x+25)∘(4x+25)^\circ(4x+25)∘. What is xxx?
Correct answer: A
Consecutive angles are supplementary.
The diagonals of parallelogram ABCDABCDABCD meet at EEE. The lengths in centimeters satisfy
What is the full length ACACAC?
Correct answer: D
Set the two pieces of the same diagonal equal.
Each half is 131313 cm, so the full diagonal is 262626 cm.
In parallelogram ABCDABCDABCD, diagonal ACACAC crosses the parallel sides BCBCBC and ADADAD. Which angle is congruent to ∠BCA\angle BCA∠BCA by alternate interior angles?
Correct answer: B
Use the side BCBCBC at CCC and the parallel side ADADAD at AAA. The common transversal is ACACAC, so the matched angle at AAA is ∠DAC\angle DAC∠DAC.
In parallelogram ABCDABCDABCD, diagonal ACACAC gives two alternate interior-angle pairs, and ACACAC is the common included side. Which conclusion uses those facts directly?
The angle at AAA in triangle ABCABCABC matches the angle at CCC in triangle CDACDACDA, while CCC matches AAA. The shared side lies between those angles, so the ordered match is ASA.
Diagonal ACACAC of parallelogram ABCDABCDABCD splits angle DABDABDAB into 26∘26^\circ26∘ and 41∘41^\circ41∘ parts. What is the measure of angle ABCABCABC?
First add the parts to find the whole angle at AAA.
Then use supplementary consecutive angles.
Parallelogram ABCDABCDABCD has diagonal intersection OOO. Under the half-turn about OOO, which segment is the image of side ABABAB?
The half-turn sends AAA to CCC and BBB to DDD. A rigid motion sends a segment to the segment joining its endpoint images, so ABABAB maps to CDCDCD.
Which list can be the four angles of a parallelogram ABCDABCDABCD, in boundary order?
For the alternating 85∘85^\circ85∘ and 95∘95^\circ95∘ list, each opposite pair matches and each consecutive pair adds to 180∘180^\circ180∘. A parallelogram drawn with an 85∘85^\circ85∘ corner realizes those four measures.
In the proof that parallelogram diagonals bisect each other, triangles ABEABEABE and CDECDECDE have two alternate interior-angle pairs. Which previously proved fact supplies the included side?
The included sides of the small triangles are the opposite sides ABABAB and CDCDCD. Their congruence was proved first using the larger triangles. It may therefore be used without assuming diagonal bisection.
The diagonals of parallelogram ABCDABCDABCD meet at EEE. If AEAEAE is 555 cm and BEBEBE is 333 cm, which pair gives the full diagonal lengths?
Each full diagonal has two copies of its own half length.
The solid outline is a parallelogram. The dashed red outline is its reflection in the horizontal line shown. What does the displayed mismatch establish by itself?
The point AAA reflects to A′A'A′ outside the set of original vertices, so this proposed axis fails. Ruling out every possible axis needs a further argument; a single failed fold does not do that.
A quadrilateral is given to be a parallelogram. Under the inclusive trapezoid definition used here, which statement is correct?
A trapezoid needs at least one parallel opposite-side pair. A parallelogram has two, so it satisfies that definition. This naming convention does not add reflection or diagonal properties.
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