Question

lines l and m are parallel lines cut by the transversal line t. which angles are congruent to ∠1?

Explanation:

Step1: Identify vertical - angle relationship

$\angle1$ and $\angle3$ are vertical angles, so $\angle1=\angle3$.

Step2: Identify corresponding - angle relationship

$\angle1$ and $\angle5$ are corresponding angles, so $\angle1 = \angle5$.

Step3: Identify alternate - exterior - angle relationship

$\angle1$ and $\angle7$ are alternate - exterior angles, so $\angle1=\angle7$.

Answer:

$\angle3$, $\angle5$, $\angle7$