Lines ℓ₁ and ℓ₂ are parallel. A transversal crosses them as shown. If ∠1 = 125°, what is ∠2?
A55°
B65°
C125°
D135°
Explanation
📌 Step 1: Identify the angle relationship ∠1 and ∠2 are co-interior angles (same-side interior) — they are between the parallel lines on the same side of the transversal.
📌 Step 2: Apply the co-interior angle theorem Co-interior angles are supplementary (add to 180°). ∠2 = 180° − 125° = 55°