Establish Angle Facts Using Arguments Practice Test

Since $\ell$ and $m$ are parallel, all eight angles formed are equal, so $m\angle 1 = m\angle 5$.

Because the transversal crosses both lines, $\angle 1$ and $\angle 5$ must add to $360^\circ$, so they are equal.

Corresponding angles are always supplementary, so $m\angle 1 + m\angle 5 = 180^\circ$.

Slide (translate) the intersection point on $\ell$ straight down along the transversal until it lands on line $m$. Because $\ell \parallel m$, the transversal meets both lines at the same angle, and translations preserve angle measure, so $m\angle 1 = m\angle 5$.