Sometimes it is helpful to hear or read the thought process of others. In this article, you’ll find my thought process on ways to remember the different types of angles. Hopefully, these math tips will help you as they have helped other students.

The following math tips will help remember how to identify same-side angles and its key concept.

We begin with the assumption that lines a and b are parallel and another line called a transversal intersects both lines. In the above diagram, the transversal is the red line.

Also, let’s get an understanding of what angles are considered interior and exterior.

Exterior - Based upon the diagram above, the exterior represents the angles immediately above line a (<1 and <2) and the angles immediately below line b (<7 and <8).

Interior - Based on the diagram above, the interior is referred to those angles located between lines a and line b. (<3, <4, <5, <6)


I. Same-side interior angles:
Thought process: What is the definition of interior? Inside
The same side of what..? The same side of that vertical red line in the above diagram called a transversal.
Based on the diagram above, the inside is referred to those angles located between lines a and line b
So, what angles are inside and located on the same side? <4 and <6 another pair is <3 and <5


II. Same-side exterior angles:
Thought process: What is another word for exterior? Outside
The same side of what..? The same side of that vertical red line in the above diagram called a transversal.
Based upon the diagram above, the outside or exterior represents the angles immediately above line a and the angles immediately below line b. Take a look.
Thus, the angles that are on the same side and exterior on the are (<1 and <7) and (<2 and <8).
Why not <1 and <2? Although they are both exterior angles, each angle is on a different side of the red line (transversal). Therefore, they are not same-side exterior.

Now, there are theorems that states that if a transversal line intersects two parallel lines, then the same-side interior and same-side exterior are supplementary. Supplementary means the sum of the angles equal 180 degrees.

I engrained this into my mind by writing down the words, Same-side – S upplementary and made the mental note that each word begins with “S. Therefore, it’s easier to remember same-side interior angles and same-side exterior angles are supplementary.