Question

1. find the measure of ∠1. justify your answer.

m∠1 = 75 because corresponding angles of parallel lines are supplementary.
m∠1 = 105 because corresponding angles of parallel lines are supplementary.
m∠1 = 105 because corresponding angles of parallel lines are congruent.
m∠1 = 75 because corresponding angles of parallel lines are congruent.

Explanation:

Step1: Identify angle - relationship

Lines $\ell$ and $m$ are parallel and $t$ is a transversal. $\angle1$ and the $75^{\circ}$ angle are corresponding angles.

Step2: Apply angle - property

Corresponding angles of parallel lines are congruent. So, $m\angle1 = 75^{\circ}$.

Answer:

D. $m\angle1 = 75$ because corresponding angles of parallel lines are congruent.