Bisecting an Angle by Paper Folding

An angle can be bisected using only a straightedge and folding the paper.

To bisect ∠ ABC, the following two steps can be done. If available, it is recommended to use tracing paper.

1

Fold the Paper

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Fold the paper in such a way that BA lies on BC. Then, unfold the paper. Notice that B is in the crease.

2

Draw the Angle Bisector

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Using a straightedge, and starting at B, draw the line that the crease made in the paper. This line is the angle bisector of ∠ ABC.