Question: User: Which angles are vertical to each other?
∠1 and ∠5
∠1 and ∠3
∠3 and ∠6
∠4 and ∠6
Graph: Two slanted parallel lines are cut by a slightly descending transversal; left intersection has angles 3 (upper-left), 4 (upper-right), 2 (lower-left), 1 (lower-right), and right intersection has angles 7 (upper-left), 8 (upper-right), 6 (lower-left), 5 (lower-right). The correct vertical-angle pair is ∠1 and ∠3, with position_hint = top-left.
1. **State the problem:** Identify which pairs of angles are vertical angles.
2. **Definition:** Vertical angles are pairs of opposite angles made by two intersecting lines. They are always equal.
3. **Analyze the intersections:**
- At the left intersection, angles are labeled as follows:
- Upper-left: $\angle 3$
- Upper-right: $\angle 4$
- Lower-left: $\angle 2$
- Lower-right: $\angle 1$
4. **Identify vertical angles at the left intersection:**
- Vertical angles are opposite pairs:
- $\angle 3$ and $\angle 1$
- $\angle 4$ and $\angle 2$
5. **Check the given options:**
- $\angle 1$ and $\angle 5$: These are at different intersections, not vertical.
- $\angle 1$ and $\angle 3$: These are vertical angles at the left intersection.
- $\angle 3$ and $\angle 6$: Different intersections, not vertical.
- $\angle 4$ and $\angle 6$: Different intersections, not vertical.
6. **Conclusion:** The vertical angle pair is $\angle 1$ and $\angle 3$.
**Final answer:** $\boxed{\angle 1 \text{ and } \angle 3}$