http://www.ck12.org Chapter 1. Basics of Geometry
1.3 Congruent Angles and Angle Bisectors
Here you’ll learn how to find unknown values using the definitions of angle congruency and angle bisector. You’ll
also learn how to construct an angle bisector.
What if you knew that an angle was split exactly in half? How could you use this information to help you solve
problems? After completing this Concept, you’ll be able to bisect an angle and solve problems related to angle
bisectors.
Watch This
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Click image to the left for more content.CK-12 Foundation: Chapter1CongruentAnglesandAngleBisectorsA
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Click image to the left for more content.James Sousa:Angle Bisectors
Watch the first part of this video.
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Click image to the left for more content.James Sousa:Angle Bisector Exercise
Guidance
When two rays have the same endpoint, an angle is created.
Here,
−→
BAand−→
BCmeet to form an angle. An angle is labeled with an “^6 ” symbol in front of the three letters used to
label it. This angle can be labeled^6 ABCor^6 CBA.Always put the vertex (the common endpoint of the two rays)
in the middle of the three points.It doesn’t matter which side point is written first.