If Angle 8 is congruent to angle 10 and Angle 1 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.

Congruent shapes has the same size or the same shape. Hence, if 1 holds the mirror in front of an objects then it would seem same. Many shapes such as a triangle, a circle, a quadrilateral and all other shapes could be congruent types.

We have been given two conditions that:

Angle 8 is congruent to angle 10
Angle 1 is congruent to angle 7

When all the pair of lines that are r,s or t,u are parallel, then the angles <8 and <10 and <1 and <7 become opposite angle, which are always =. Even if 1 pair of lines is't parallel, these conditions won;t hold true.

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