# Understanding Angle Bisectors: Everything You Need to Know!

In geometry, an angle bisector plays a crucial role in constructing various shapes and solving geometric problems. But what exactly is an angle bisector, and how does it work?

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Keep reading to explore the definition of an angle bisector, its properties, how to find it, and some of its applications.

## What Is An Angle Bisector?

An angle bisector is a line or ray that divides an angle into two equal angles. This line or ray starts from the vertex of the angle and extends to the opposite side, cutting it into two equal parts. Essentially, it splits the angle in half, creating two smaller, congruent angles.

Angle bisectors can be identified in any type of triangle, from the most basic to the most complex. For example, in triangle ABC, the angle bisector BD divides angle B into two equal parts, angle ABD and angle CBD.

## Properties of an Angle Bisector

One of the key properties of an angle bisector is that it cuts the opposite side of the triangle into two segments that are proportional to the adjacent sides of the triangle; this property is known as the Angle Bisector Theorem.

In addition, the angle bisector always lies inside the triangle because it does not extend beyond its opposite side. The angle bisector is perpendicular to the median of the triangle that passes through the vertex of the angle.

## How to Construct An Angle Bisector Using a Compass

To find the angle bisector of a given angle, we can use a compass. Here is how to construct an angle bisector using a compass:

• First, mark the vertex of the angle and draw the two sides of the angle.
• Then, using a compass, draw two arcs from each endpoint of the angle that intersects the two sides of the angle.
• Next, draw a straight line connecting the vertex of the angle to the point where the two arcs intersect. This line is the angle bisector.

I encourage you to watch the video below to learn more about how to construct an angle bisector using a compass.

## Applications of the Angle Bisector

The angle bisector has many applications in different fields, including mathematics, physics, and engineering. For example, it can be used to calculate the distance between a point and a line, to find the location of an object in space, and to design complex structures.

Moreover, the angle bisector is used extensively in construction and architecture to create symmetrical buildings and designs.

In geometry, the Angle Bisector Theorem is used to solve various geometric problems, such as finding the length of sides, the measure of angles, or the area of a triangle. For example, if you know the length of two sides and the measure of the angle between them, you can use the Angle Bisector Theorem to find the length of the third side of the triangle.

Similarly, if you know the length of one side and the measure of two angles that include it, you can use the Angle Bisector Theorem to find the length of the adjacent side.

Another interesting application of the angle bisector is in navigation. The angle bisector can be used to determine the position of a ship or a plane relative to its destination. This technique is known as triangulation, and it involves using the angle bisector to create a triangle between the observer, the object, and the destination.

By measuring the angles of the triangle and knowing the distance between the observer and the object, it is possible to calculate the distance between the observer and the destination.

## Types of Angle Bisectors

There are different types of angle bisectors, depending on the geometric shape you are working with and the angle you are bisecting. In a triangle, there are three types of angle bisectors:

• The incenter (which is the intersection of all three angle bisectors)
• The circumcenter (which is the center of the circumcircle that passes through all three vertices of the triangle)
• And the orthocenter (which is the intersection of all three altitudes of the triangle)

If you want to explore more about angle bisector and the angle bisector theorem, I encourage you to check Khan Academy or watch this video or the video below.