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Angle Bisector Construction

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About This MicroSim

This interactive tutorial demonstrates the classical compass and straightedge construction for bisecting an angle. Adjust the slider to try different starting angles.

Construction Steps

Step Action
1 Draw arc from B intersecting both rays at P and Q
2 Draw arc from P toward the interior
3 Draw arc from Q with same radius - find intersection D
4 Draw ray BD (the angle bisector)
5 Verify: ∠ABD ≅ ∠DBC

How to Use

  1. Adjust the slider to change the original angle (40° to 140°)
  2. Click "Next" to advance through steps
  3. Click "Auto" to watch the full animation
  4. Click "Reset" to start over

Why It Works

The arcs from P and Q have equal radii, creating point D that is equidistant from both rays of the original angle. This ensures the bisector divides the angle exactly in half.

Learning Objectives

  • Perform angle bisection construction
  • Verify that the two resulting angles are congruent
  • Apply the construction to any angle

Bloom's Taxonomy Level

Applying and Evaluating - Performing construction and verifying results.

Iframe Embed Code

<iframe src="https://dmccreary.github.io/geometry-course/sims/angle-bisector-construction/main.html"
        height="652px"
        width="100%"
        scrolling="no"></iframe>