Endpoint in Math – Definition, Formula, Examples, Facts
9 minutes read
Created: January 2, 2024
Last updated: January 14, 2024
At Brighterly, we understand how the world of mathematics can seem complex and daunting. It is a language of its own, filled with various concepts and terminologies. But don’t fret! Our mission at Brighterly is to make learning these mathematical concepts not only easier, but fun as well. Today, we’re going to take a deep dive into a foundational geometry concept, the “endpoint”. This simple yet crucial concept forms the backbone of various other concepts in geometry.
From line segments and rays to finding lengths and bisecting lines, we’re going to unravel the magic of endpoints in the realm of mathematics, illuminating your learning journey with Brighterly. So, buckle up and get ready to explore this fascinating world of endpoints, equipped with definitions, formulas, examples, and interesting facts!
Endpoint in Math
The word “endpoint” is derived from the words “end” and “point.” In mathematics, an endpoint often refers to a point that marks the end of a line segment or the starting point of a ray. Imagine you draw a line on a piece of paper, where you start and stop that line, those two points are called endpoints. Simple, isn’t it?
Endpoints play a key role in different mathematical concepts, including line segments, rays, and intervals on a number line. Understanding this term will make solving geometric problems a breeze!
What Is a Line Segment?
A line segment is a part of a line that is bounded by two distinct end points, and contains every point on the line between its endpoints. Think of a stick – it has a starting point and an ending point. This is different from a “line,” which continues infinitely in both directions.
What Is a Ray?
A ray is a line that starts at a certain point and goes off in a certain direction to infinity. So, a ray has one endpoint where it starts, and then it goes on forever in one direction. Imagine a flashlight; it starts at one point (where the light is produced) and then the light spreads out infinitely.
What Is an Endpoint in Geometry?
In geometry, an endpoint can have two definitions depending on what it’s referring to. When talking about a line segment, the endpoint refers to either of the two points that mark the end of the line segment. In the case of a ray, the endpoint is where the ray starts before it goes off infinitely in one direction.
Finding the Length of a Line Segment Using the Endpoints
Calculating the length of a line segment is pretty straightforward when you know the coordinates of the endpoints. You can use the distance formula, derived from the Pythagorean theorem, to find the length of a line segment in a coordinate plane.
Bisecting a Line Segment Using Endpoints
Bisecting a line segment means dividing it into two equal parts. The midpoint formula is used to find the point that bisects a line segment, and it is the average of the xcoordinates and the ycoordinates of the endpoints.
How to Find the Endpoint of a Line Segment?
If you know the midpoint and one endpoint of a line segment, you can find the other endpoint. How? It’s as simple as using the midpoint formula in reverse! By treating the midpoint as the average and knowing one endpoint, we can find the other.
The Formula to Find the Endpoint: Endpoint Formula
The endpoint formula is derived from the midpoint formula. If M(x1, y1) is the midpoint and A(x, y) is the known endpoint, then the coordinates B(x2, y2) of the other endpoint are given by x2 = 2×1 – x and y2 = 2y1 – y.
How Do We Name Objects Using the Endpoints?
In geometry, we often name line segments and rays by their endpoints. For example, a line segment with endpoints A and B is named segment AB, while a ray with endpoint C going through point D is named ray CD.
What is Endpoint Formula?
In mathematics, especially geometry, you may come across situations where you know the midpoint of a line segment and one endpoint, and you are required to find the coordinates of the other endpoint. This is where the Endpoint Formula comes into play.
The formula is derived from the Midpoint Formula which states that the midpoint M(x1, y1) of a line segment with endpoints A(x, y) and B(x2, y2) is given by the average of the xcoordinates and the ycoordinates of the endpoints, or:
x1 = (x + x2) / 2, and
y1 = (y + y2) / 2.
By rearranging these equations, we can find the coordinates of the unknown endpoint B(x2, y2):
x2 = 2×1 – x, and
y2 = 2y1 – y.
So, if you know the coordinates of the midpoint and one endpoint, you can calculate the coordinates of the other endpoint using the Endpoint Formula!
Practice Problems on Endpoint
Practicing is the best way to consolidate your understanding of a concept, and endpoints are no different. Let’s dive into a couple of practice problems:

Problem: If the midpoint of a line segment is M(3, 4) and one endpoint is A(1, 2), find the coordinates of the other endpoint B.
Solution: Using the endpoint formula:
x2 = 2×1 – x = 23 – 1 = 5, and
y2 = 2y1 – y = 24 – 2 = 6.Therefore, the coordinates of endpoint B are (5, 6).

Problem: Given that the midpoint of a line segment is M(1, 2) and one endpoint is A(3, 5), find the other endpoint B.
Solution: Using the endpoint formula:
x2 = 2×1 – x = 2*(1) – (3) = 1, and
y2 = 2y1 – y = 2*2 – 5 = 1.Therefore, the coordinates of endpoint B are (1, 1).
Conclusion
Endpoints are one of those essential tools in the toolkit of mathematics. By defining the boundaries of line segments or directing the path of rays, they play a pivotal role in our understanding of geometry. Whether you’re calculating distances or bisecting lines, endpoints provide the muchneeded foothold.
At Brighterly, we believe in transforming mathematical complexities into simplified learning experiences. We hope this exploration of endpoints has turned this seemingly abstract concept into something tangible and easy to understand. As you venture further into the world of geometry, you’ll discover that mastering the concept of endpoints has given you the stepping stones to navigate through more advanced concepts. Remember, every expert was once a beginner. Keep practicing and let the world of math unfold its wonders to you!
Frequently Asked Questions on Endpoint
What is an endpoint in math?
An endpoint in mathematics refers to the point that either terminates a line segment or initiates a ray. It is basically a “boundary marker” for line segments and a “starting marker” for rays.
What is a line segment?
A line segment is a part of a line that has two endpoints. It includes every point on the line that lies between its two endpoints. Think of a line segment as a closeddoor corridor – it has a definite beginning and a definite end.
What is a ray?
A ray, in contrast to a line segment, is a part of a line that has one endpoint and extends indefinitely in one direction. If a line segment is a closeddoor corridor, a ray is an opendoor corridor – it has a starting point, but no ending point; it goes on forever.
What is the endpoint formula?
The endpoint formula is a practical tool in geometry that allows you to calculate the coordinates of an unknown endpoint if you know the coordinates of the midpoint and one endpoint of a line segment. The formula is as follows:
If M(x1, y1) is the midpoint and A(x, y) is the known endpoint, then the coordinates B(x2, y2) of the other endpoint are given by x2 = 2×1 – x and y2 = 2y1 – y. This formula is derived from the midpoint formula and can be utilized in various geometry problems.
AfterSchool Math Program
 Boost Math Skills After School!
 Join our Math Program, Ideal for Students in Grades 18!
Kid’s grade
AfterSchool Math Program
Boost Your Child's Math Abilities! Ideal for 1st8th Graders, Perfectly Synced with School Curriculum!