Question

if a || b and m∠7 = 115°, find m∠2. a cannot be determined b 180° c 65 d 115

Explanation:

Step1: Identify angle - pair relationship

$\angle7$ and $\angle5$ are vertical angles. Vertical angles are equal. So $m\angle5 = m\angle7=115^{\circ}$.

Step2: Use the property of parallel lines

Since $A\parallel B$, $\angle5$ and $\angle2$ are alternate - interior angles. Alternate - interior angles formed by two parallel lines and a transversal are equal. So $m\angle2=m\angle5 = 115^{\circ}$.

Answer:

D. 115