# In which diagram are angles 1 and 2 vertical angles?

Vertical angles are a pair of non-adjacent angles formed by the intersection of two straight lines.

## Answer: (a)

Vertical angles are located across from one another in the corners of the "X" formed by two straight lines.

**Explanation:**

(a) Clearly, ∠1 and ∠2 are not adjacent angles. So, ∠1 and ∠2 are vertical angles.

(b) Clearly, ∠1 and ∠2 are adjacent angles. So, ∠1 and ∠2 are not vertical angles.