Segment Addition Postulate: Definition & Examples

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: The Reflexive Property of Equality: Definition & Examples

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:00 Segment Addition…
  • 0:46 Examples
  • 2:49 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Karin Gonzalez

Karin has taught middle and high school Health and has a master's degree in social work.

In this lesson, we will review the definition of the segment addition postulate. We will also look at examples to clearly illustrate how this concept works in the real-world.

Segment Addition Postulate Defined

The segment addition postulate states that if we are given two points on a line segment, A and C, a third point B lies on the line segment AC if and only if the distances between the points meet the requirements of the equation AB + BC = AC. See Diagram 1 to gain a clearer understanding of this postulate definition.

Diagram 1: Segment Addition Postulate.
Segment Addition Postulate- Diagram 1.

Remember that a line segment is part of a line bound by two clear end points. It is comprised of a bunch of points between those two end points.

An easier way of stating the segment addition postulate is that if point B lies on line segment AC, then AB + BC will equal AC. That seems pretty simple, does it not?


Let's take a look at some different examples.

Example 1:

Let us look at a line segment on our body: our leg! Our leg has an endpoint A, the top of your thigh, and endpoint C, your ankle. Imagine the length of your entire leg (from endpoint A to C) measures 25 inches and the length from point B, your knee, to endpoint C is 12 inches. According to the segment addition postulate, what would be the length of Endpoint A to point B?

AB (unknown) + BC (12) = AC (25)

AB = 25 - 12

AB = 13 inches

Example 2:

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account