Geometry - Regarding Parallel Lines and Angles

[kiricole03]

Geometry - pg 132 Problem Set #17 - I don't know whether those lines are parallel. There are rules when a transversal cuts through parallel lines, i.e. interior angles are equal, exterior angles are equal, interior angles on the same side of the transversal equal 180, etc. Can these rules be used in this problem even without knowing whether the lines are parallel? I used the supplementary angle rule to answer the question . . .

[tommywallach]

Hey Kiri,

Nope. If you aren't told lines are parallel, then you can't assume it, and those all those inferences are no longer true.

-t