Question

line ab is parallel to line cd. what is the measure of ∠3? 160° 180° 80° 90°

Explanation:

Step1: Identify corresponding angles

Since $AB\parallel CD$, $\angle 3$ and the angle marked $80^{\circ}$ are corresponding angles.

Step2: Apply corresponding - angles property

Corresponding angles formed by two parallel lines and a transversal are equal. So $\angle3 = 80^{\circ}$.

Answer:

C. $80^{\circ}$