12 multiple-choice questions, progressively harder.
Convex ABCDABCDABCD has side lengths in centimeters.
Which value makes both opposite-side pairs congruent?
Solution
Correct answer: C
Check the first pair:
The other pair requires
Both pairs have positive equal lengths at that value.
Convex ABCDABCDABCD has these side lengths in the same unit.
Which value of xxx makes both opposite-side pairs congruent?
Correct answer: A
The first pair requires
so x=4x=4x=4. The second requires
so x=5x=5x=5. One value cannot meet both requirements. The side test cannot be completed with these expressions.
Diagonals ACACAC and BDBDBD of convex ABCDABCDABCD meet at EEE. Their parts have lengths in the same unit.
Which values make both diagonals bisect each other?
x=4x=4x=4
y=5y=5y=5
x=5x=5x=5
y=4y=4y=4
y=2y=2y=2
x=11x=11x=11
Correct answer: B
Compare parts on the same diagonal:
For the other diagonal,
The resulting half-lengths are 131313 and 555, both positive.
In convex ABCDABCDABCD, both opposite-angle pairs are congruent. Angle AAA measures (2x+10)∘(2x+10)^\circ(2x+10)∘ and angle CCC measures (4x−30)∘(4x-30)^\circ(4x−30)∘. What is the measure of angle BBB?
Correct answer: D
Set the opposite measures equal:
Thus angle AAA is 50∘50^\circ50∘. The complete opposite-angle test proves a parallelogram, so consecutive angles are supplementary:
Convex ABCDABCDABCD has two side equalities.
After drawing diagonal BDBDBD, which ordered triangle correspondence is guaranteed by these matches and SSS?
Match ABABAB with CDCDCD, ADADAD with CBCBCB, and the common BDBDBD with DBDBDB. The vertex correspondence is A↔CA\leftrightarrow CA↔C, B↔DB\leftrightarrow DB↔D, and D↔BD\leftrightarrow BD↔B, giving the stated order.
Diagonals of convex ABCDABCDABCD bisect each other at EEE. Which reason proves △AEB≅△CED\triangle AEB\cong\triangle CED△AEB≅△CED?
The givens give two side matches.
Angles AEB,CEDAEB,CEDAEB,CED are vertical and lie between those side pairs. Thus SAS applies, without assuming parallel sides.
In convex ABCDABCDABCD, angles A,CA,CA,C both measure ppp, and angles B,DB,DB,D both measure qqq. Which equation turns this evidence into supplementary consecutive angles?
The quadrilateral angle sum is
Dividing by 222 gives p+q=180∘p+q=180^\circp+q=180∘. The common measures need not be equal.
In the shown convex ABCDABCDABCD, the givens include a parallel pair and a congruent pair.
Which fact proves that this particular quadrilateral is not a parallelogram?
Every parallelogram has congruent opposite sides. Here the parallel bases have lengths 121212 and 666, so they are unequal. The congruent sloping sides do not repair that failure.
Diagonals of convex ABCDABCDABCD meet at EEE. The parts have lengths in the same unit.
Which conclusion is certain?
Although ACACAC is bisected, BEBEBE and EDEDED are unequal. Every parallelogram has both diagonals bisected. Failure of this necessary condition excludes a parallelogram.
Convex ABCDABCDABCD has this evidence about one opposite-side pair.
With diagonal ACACAC, which included-angle equality supports SAS for triangles BACBACBAC and DCADCADCA?
Transversal ACACAC crosses the given parallel lines AB,CDAB,CDAB,CD, so ∠BAC\angle BAC∠BAC and ∠DCA\angle DCA∠DCA are equal alternate interior angles. They lie between the given equal sides and the common diagonal. The other listed equalities cannot be assumed before proving the needed structure.
In convex ABCDABCDABCD, diagonals meet at EEE. The parts have lengths in centimeters.
Which conclusion is justified?
The given pairs compare different diagonals. On ACACAC, its halves are 222 and 333, so it is not bisected. This violates a necessary parallelogram property, even though each whole diagonal is 555 cm.
The diagonals of convex ABCDABCDABCD bisect each other at EEE. SAS gives two congruences.
Which conclusion completes a valid side-based proof of a parallelogram?
AB=CDAB=CDAB=CD
BC=ADBC=ADBC=AD
AE=BEAE=BEAE=BE
EC=EDEC=EDEC=ED
Corresponding sides of the first congruence give AB=CDAB=CDAB=CD.
Corresponding sides of the second give BC=ADBC=ADBC=AD.
Both opposite-side pairs are congruent, so the previously proved side test establishes a parallelogram.
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