Angle Bisector: Definitions and Examples

Angle Bisector: Definitions, Formulas, & Examples

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    An angle bisector is a line that divides an angle into two equal angles. In other words, it is a line that bisects, or cuts in half, an angle. Angle bisectors are important in geometry because they allow us to divide an angle into two equal parts, which is useful for solving a variety of problems.

    In order to understand angle bisectors, it is important to first understand what an angle is. An angle is formed when two rays, or half-lines, share a common endpoint. This common endpoint is called the vertex of the angle. The rays that form the angle are called the sides of the angle. The size of an angle is measured in degrees, with a full circle being 360 degrees.

    There are several types of angles, including acute angles, right angles, obtuse angles, and straight angles. Acute angles are angles that measure less than 90 degrees. Right angles are angles that measure exactly 90 degrees. Obtuse angles are angles that measure more than 90 degrees, but less than 180 degrees. Straight angles are angles that measure exactly 180 degrees.

    Now that we have a basic understanding of angles, let’s delve deeper into angle bisectors. As mentioned earlier, an angle bisector is a line that divides an angle into two equal angles. This means that if we draw an angle bisector through the vertex of an angle, the two resulting angles will be equal in size.

    One way to visualize an angle bisector is to think of it as a “slice” of the angle. Just as a pizza slice cuts a pizza into two equal parts, an angle bisector cuts an angle into two equal parts.

    There are several properties of angle bisectors that are important to understand. First, angle bisectors always divide an angle into two equal parts. This is true regardless of the size of the angle. Second, angle bisectors always pass through the vertex of the angle. Third, angle bisectors always bisect the sides of the angle.

    Now that we have a basic understanding of angle bisectors, let’s look at some examples.

    Example 1:

    In this example, we have an acute angle with a vertex at point A and sides AB and AC. We want to find the angle bisector of this angle.

    To do this, we draw a line through the vertex of the angle that divides the angle into two equal parts. The resulting line is the angle bisector.

    Example 2:

    In this example, we have an obtuse angle with a vertex at point D and sides DE and DF. We want to find the angle bisector of this angle.

    To do this, we draw a line through the vertex of the angle that divides the angle into two equal parts. The resulting line is the angle bisector.

    Example 3:

    In this example, we have a right angle with a vertex at point G and sides GH and GI. We want to find the angle bisector of this angle.

    To do this, we draw a line through the vertex of the angle that divides the angle into two equal parts. The resulting line is the angle bisector.

    Example 4:

    In this example, we have a straight angle with a vertex at point J and sides JK and JL. We want to find the angle bisector of this angle.

    To do this, we draw a line through the vertex of the angle that divides the angle into two equal parts. The resulting line is the angle bisector.

    Example 5:

    In this example, we have an acute angle with a vertex at point M and sides MN and MO


    Angle Bisector:

    Illustration

    Illustration

    Definition

    The (interior) bisector of an angle, also called the internal angle bisector, is the line or line segment that divides the angle into two equal parts. The angle bisectors meet at the incenter I, which has trilinear coordinates 1:1:1. The length t_1 of the bisector A_1 T_1 of angle A_1 in the above triangle Δ A_1 A_2 A_3 is given by t_1^2 = a_2 a_3[1 - a_1^2/(a_2 + a_3)^2], where t_i congruent (A_i T_i)^_ and a_i congruent (A_j A_k)^_. The points T_1, T_2, and T_3 have trilinear coordinates (0, 1, 1), (1, 0, 1), and (1, 1, 0), respectively, and form the vertices of the incentral triangle.

    Related Wolfram Language symbol

    AngleBisector

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