12 multiple-choice questions, progressively harder.
The rectangular outline has vertices (−5,−2)(-5,-2)(−5,−2), (5,−2)(5,-2)(5,−2), (5,2)(5,2)(5,2), and (−5,2)(-5,2)(−5,2). Does reflection across y=xy=xy=x match it?
Solution
Correct answer: C
The diagonal reflection exchanges coordinates. That vertex maps to (−2,−5)(-2,-5)(−2,−5), below every point of the outline. One failed point rejects the candidate.
A triangular outline joins U(−2,1)U(-2,1)U(−2,1), V(4,1)V(4,1)V(4,1), and W(1,6)W(1,6)W(1,6). Which fact establishes symmetry across x=1x=1x=1?
Correct answer: A
The vertical mirror swaps horizontal positions -2 and 4, equally spaced from 1, and fixes the vertex with horizontal coordinate 1. The reflected sides join the image endpoints, so the entire boundary matches.
A figure has least positive matching angle 36∘36^\circ36∘ about O and finite rotational order. What is its order, including identity?
Correct answer: D
Count equally spaced matches in a full turn.
360÷36=10360\div36=10360÷36=10
The ten rotations include identity once.
A figure has finite rotational order 6 about C, counting identity. How many of these matching rotations are nonidentity?
Correct answer: B
Remove the one identity mapping from the six distinct rotations.
6−1=56-1=56−1=5
A square boundary centered at the origin has corners (±5,±5)(\pm5,\pm5)(±5,±5). The figure also includes four identical point marks. Three marks are at (−4,1)(-4,1)(−4,1), (4,−1)(4,-1)(4,−1), and (2,3)(2,3)(2,3). Where must the fourth be for point symmetry about the origin?
The square boundary matches a half-turn. The first two marks already form an opposite pair; the mark at (2,3) needs its half-turn partner (-2,-3). Then the entire marked figure matches.
For the exact block H outline shown, which tests succeed about its bounding-box center O?
The two equal upright bars exchange under the vertical fold and under a half-turn. The horizontal center bar stays in place. The horizontal fold pairs the top and bottom halves of each upright bar. All three tests match the whole outline.
The figure is a circle together with two identical marks at opposite ends of one diameter. The marks belong to the figure. What is its rotational order about O?
A 180∘180^\circ180∘ turn swaps the marks and matches the circle. The only other matching rotation in a full turn is identity; other angles put the marks at unmarked circle positions. The whole figure therefore has order 2.
An unmarked square is changed by adding one point exactly at its center. The new figure includes both the boundary and that point. What happens to its rotational order about that center?
Each quarter-turn still pairs the square boundary, and the added center point is fixed by every such turn. No new angle can match the square boundary, so the order stays 4.
A rectangle is centered at (3,2)(3,2)(3,2). A corner is P(−1,−1)P(-1,-1)P(−1,−1). What must its opposite corner be for the half-turn symmetry?
P lies four units left and three below the center. A half-turn puts its image four right and three above the center.
3+4=73+4=73+4=7
2+3=52+3=52+3=5
A square's matching angles are recorded as 0∘0^\circ0∘, 90∘90^\circ90∘, 180∘180^\circ180∘, 270∘270^\circ270∘, and 360∘360^\circ360∘. What is the corrected count of distinct rotations?
The 0-degree and 360-degree entries both give identity. Retain one of them and the three nonidentity quarter-turn multiples.
An unmarked square is turned 90 degrees clockwise about its center, then tested again from its original position with 90 degrees counterclockwise. Which test matches?
Both directions give matching quarter-turns. They exchange corners in opposite orders, but each still carries the whole square onto itself.
A triangle is constructed by joining three points on a circle, equally spaced by 120∘120^\circ120∘ turns about O. Which statement about its half-turn is correct?
The triangle matches at 0∘0^\circ0∘, 120∘120^\circ120∘, and 240∘240^\circ240∘. A 180∘180^\circ180∘ turn sends a vertex to a direction halfway between two vertex rays, so its image is not a vertex. The guide circle is not the tested triangular figure.
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