Definition: Adjacent angles are two angles that share a common vertex and a common side, but do not overlap each other.
What are adjacent angles?
Adjacent means next to. Two angles are adjacent when they have the same vertex, share one ray, and sit on opposite sides of that ray.
How do you recognize them?
Imagine opening a pair of scissors with a pin in the middle. Angles that touch along a blade, with no overlap, are adjacent. Two angles that merely share a vertex but not a side are not adjacent.
What do their measures do?
Add them to get the combined angle. Adjacent angles measuring 35 degrees and 48 degrees make an 83 degree angle together. If they form a straight line, they are a linear pair and sum to 180. If they form a corner, they sum to 90 degrees.
How do you solve with a missing angle?
An angle of 132 degrees is split by a ray into parts of x and 2x degrees. Since 3x = 132, then x = 44, and the parts are 44 and 88.
What is a common mistake?
Assuming adjacent angles are always supplementary or complementary. They are only those if their total is 180 or 90 degrees.