Angles 1 and 2 form a linear pair when they are adjacent angles that are formed when two lines intersect. When two lines cross each other, they create four angles, and if angle 1 and angle 2 are situated next to each other and add up to 180 degrees, they are considered a linear pair.
For example, consider a diagram of two intersecting lines:
A
|\
| \
| \
| \
+----B----+
| /\ |
| / \ |
| / \ |
C D
In this diagram, if we label one of the angles formed at the intersection point as angle 1 and the adjacent angle as angle 2, then angles 1 and 2 together create a straight line along line AB.
Therefore, if you see two angles that fit this description, you can confidently say that angles 1 and 2 form a linear pair. Remember, the key characteristics of a linear pair of angles are that they are:
- Adjacent (next to each other)
- Supplementary (their measures sum up to 180 degrees)
This concept is fundamental in geometry and can be applied in various contexts, including proofs and solving angle problems.