Angles 1 and 2 are considered vertical angles when they are formed by two intersecting lines, and they are located across from each other. In a typical diagram illustrating this, you’ll see two lines intersecting at a point, creating four angles in total. Vertical angles are formed when the two lines intersect in such a way that the angles opposite each other (in pairs) are equal in measure.
To identify them, look for the angles that share no common sides but are opposite each other. For instance, if lines A and B intersect, creating angles labeled as 1, 2, 3, and 4, then angles 1 and 2, as well as angles 3 and 4, are vertical angles. This equality holds true because they are formed by the same lines intersecting, leading to congruent angles.