Question

If Angle 2 is congruent to angle 4 and Angle 5 is congruent to angle 7, which describes all the lines that must be parallel?

Lines r and s are crossed by lines t and u to form 16 angles. Clockwise from top left, at the intersection of r and t, the angles are 1, 2, 3, 4; at the intersection of s and t, 5, 6, 7, 8; at the intersection of u and s, 9, 10, 11, 12; at the intersection of u and r, 13, 14, 15, 16.
Only lines r and s must be parallel.
Only lines t and u must be parallel.
Lines r and s and lines t and u must be parallel.
Neither lines r and s nor lines t and u must be parallel.

Answers

GPT-4o mini
Given the information provided, let's analyze the angle relationships to determine which lines must be parallel.

1. You stated that Angle 2 is congruent to Angle 4. Since these angles are formed by lines r and t intersecting, and lines r and s are being crossed, this indicates that lines r and s must be parallel. This is because alternate interior angles are congruent when two lines are crossed by a transversal, leading to the conclusion that the lines are parallel.

2. Additionally, you mentioned that Angle 5 is congruent to Angle 7. Angle 5 is formed by line s and line t, and Angle 7 is formed at the intersection of line s and line u. Again, since these angles are congruent, this implies that lines t and u must also be parallel due to the corresponding angle relationship.

With this reasoning, we conclude:

- Lines r and s are parallel due to Angle 2 being congruent to Angle 4.
- Lines t and u are parallel due to Angle 5 being congruent to Angle 7.

Therefore, the correct conclusion is that **lines r and s and lines t and u must be parallel.**

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