## Elementary Geometry for College Students (6th Edition)

$\angle$$1 is congruent to \angle$$3$
We can prove this because we know that $\overline{AB}$ $\parallel$ $\overline{CF}$.Since those two lines are parallel this means that they produce congruent angles when they meet another segment or line. This means that $\angle$$2 is congruent with \angle$$1$. We also know that $\angle$$3 is congruent with \angle$$2$, therefore, we can now conclude that $\angle$$1 is congruent with \angle$$3$.