with respect to transversal l, angles 6 and 12 are "alternate interior" angles
Step-by-step explanation:
Angles 6 and 12 are at different intersections. The line joining those intersections is line l.
The transversal is l.
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With respect to that transversal, angle 6 is between lines m and n crossing that transversal. Likewise for angle 12. Since both are "inside" angles, they are "interior."
Angles 6 and 12 are on opposite sides of the transversal l, so are "alternate" angles.
The alternate exterior angle theorem is when two different lines are corssed by a transversal. Essentially alternate exterior angles are when two different angles are on opposite sides of the transversal. In the given photo, 6 and 12 are on opposite sides of one transversal which makes them alternate exterior angles.