Question

in which diagram are angles 1 and 2 vertical angles?

Explanation:

Step1: Recall vertical - angle definition

Vertical angles are formed when two lines intersect. They are opposite angles.

Step2: Analyze the first diagram

In the first diagram, two lines intersect. Angles 1 and 2 are non - adjacent and opposite each other at the intersection. So they meet the definition of vertical angles.

Step3: Analyze the second diagram

In the second diagram, the two angles (1 and 2) do not have two lines intersecting such that they are opposite each other. One of the sides of the angles is common in a non - intersecting - line - pair way (not formed by two intersecting lines), so they are not vertical angles.

Answer:

The first diagram (the one with two intersecting lines where angles 1 and 2 are opposite each other at the intersection point).