Answer:
10. Not vertical
Vertical angles are a pair of non-adjacent angles formed by the intersection of two straight line.
Vertical angles are located across from one another in the corners of the "X" formed by two straight lines.
In the diagram at the right, lines m and n are straight:
∠1 and ∠2 are vertical angles.
∠3 and ∠4 are vertical angles.
∠1 and ∠3 are NOT vertical angles.
