Menu

English

The Angle Bisector

Part of the Angles section of Coddy's Geometry journey. Lesson 27 of 62.

A ray that splits an angle into two equal parts is its bisector. The single arc mark on each half is the figure’s way of saying: these two are the same size.

$An 84 degree angle split by its bisector into two equal parts of y degrees$

The whole angle in the figure measures 84°, and the bisector makes two copies of y°: 2y = 84, so y = 42. Bisect means exactly halve: the whole is twice the part, and the part is half the whole. The doubling equation carries both directions at once.

Challenge

Easy

The ray VM bisects ∠AVB, which measures 76°. Each half measures x°.

$A 76 degree angle split by its bisector into two equal parts of x degrees$

Find x.

Try it yourself

2x = 76

Solve for x

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Angles

2Straight Lines and Supplements

Angles on a Line Supplementary Angles Three Angles on a Line Write the Equation Recap: Along the Line

5Around a Point

Angles Around a Point The Missing Angle Equal Slices Four Angles, One Point Recap: The Full Turn

8Transversal Problems

Both Angles Labeled Verticals Meet Parallels From Figure to Equation Alternate with Algebra Recap: Through the Strip

11The Exterior Angle

The Exterior Angle Using the Shortcut Two Roads, One Answer Exterior in the Wild Recap: Outside View

3Right Angles and Complements

Complementary Angles Finding the Complement Perpendicular Lines Equal Parts of a Corner Recap: The Right Corner

6The Angle Bisector

The Angle BisectorBisected Expressions Bisecting a Straight Angle Recap: Split in Half

9Triangle Angle Sum

The 180 Rule Finding the Third Angle Two Unknown Angles Right Triangles Recap: The Budget

12Final Challenges

Final: The Angle Chase Final: Triangle Meets Line Final: The Full Round Final: Isosceles Chase Final: Master of Angles