Supplementary angles add up to 180 degrees. When placed next to one another, two supplementary angles form a 180 degree angle.
A 180 degree angle is a line.
If two angles are linear, then by definition, they are two angles placed next to one another, that form a straight line. ...
As you are planning your high school career, the question will arise: when should I start worrying about college, and the SAT/ACT/PSAT?
The answer is that it is never too early.
Where and when I grew up, perhaps due to a lack of other standardized tests, the SAT was used to assess eligibility for gifted and talented programs, and general academic ability, upon entry to junior high...