12 multiple-choice questions, progressively harder.
For scalene triangles,
Which order records the correspondence supplied by these side pairs?
Solution
Correct answer: B
The common vertex of the 9 and 13 sides is BBB in the first triangle and XXX in the second.
The 9 and 15 sides meet at AAA and WWW; the remaining vertices match CCC to YYY.
Thus
The given congruence and side lengths are
What is xxx?
Correct answer: D
The sides KLKLKL and QPQPQP correspond, so
Subtract 2 and divide by 3:
Triangles ABC and DEF have
Which extra equality completes an SSS argument in that order?
Correct answer: A
The already paired sides connect the first-second and first-third vertices. The remaining pair connects the second-third vertices:
Base ABABAB is fixed. Two circles, centered at AAA and BBB with fixed positive radii, meet at CCC above the base line and C′C'C′ below it. What is the relationship between the triangles ABCABCABC and ABC′ABC'ABC′?
Correct answer: C
The circle centered at AAA gives equal distances to its two intersections:
The circle centered at BBB similarly gives
The base is shared. These are three equal side pairs.
The SSS justification then shows that reflection across the base line exchanges the third vertices and fixes the endpoints.
Use this ordered congruence and these angle measures:
Find m∠Tm\angle Tm∠T.
Angle TTT corresponds to angle LLL.
The triangle angle sum gives
Congruence gives
Triangle ABCABCABC is congruent to triangle DEFDEFDEF in that order. Which statement is guaranteed even if the second triangle is drawn upside down?
Orientation does not alter the ordered match. The endpoint pairing is
Therefore ACACAC and DFDFDF are corresponding sides.
Which pair of actual triangles must be congruent from the side lengths given?
Only the pair with side-length lists (8,14,17)(8,14,17)(8,14,17) and (17,8,14)(17,8,14)(17,8,14) has three matching lengths. Pair them to get
SSS then establishes congruence.
The ordered congruence is
The corresponding lengths are
What common length do they have?
Set corresponding lengths equal:
Then
Substitute to get
The other expression also gives
Two four-sided hinged frames have four matching side lengths, but one frame has a corner angle that does not occur anywhere in the other frame. What can be concluded?
A rigid motion preserves every angle as well as every length. One frame has an angle measure absent from the other, so no rigid motion can map one exactly onto the other. Four matching side lengths do not supply a triangle SSS argument.
In a construction of △EFG\triangle EFG△EFG, the base EFEFEF is drawn first and GGG is an intersection of arcs centered at EEE and FFF. Which fact justifies EGEGEG having the chosen radius?
The arc centered at EEE is part of a circle defined by the chosen distance rrr. Because GGG lies on it,
The other arc separately fixes FGFGFG.
A rigid motion sends AAA to DDD, BBB to FFF, and CCC to EEE. Which statement records this match?
Write the images under the original ordered vertices:
Moving the letters in only one name would change the specified correspondence.
During a three-side construction, the two arcs touch at a point on the base line. What has been constructed?
A triangle requires three noncollinear vertices. At the base-line touching point, the perpendicular height is 000, so the three points are collinear and no triangle has been formed.
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