Split a corner in two
Fold a paper fan shut. Both halves match exactly.
Step 1 of 4
- A corner with two arms.
- Mark the same distance along each arm.
- Strike equal arcs from the two marks. They cross inside the corner.
- Rule a ray from the corner through the crossing.
Bisecting a corner
Mark points on the arms at the same distance from the corner. Strike arcs of the same radius from those points. Make the radius wide enough for the arcs to cross. Use the crossing inside the corner. Rule a ray from the corner through the crossing. A ray starts at a point and goes on in one direction.
That ray is the bisector of the corner. It splits the corner into two equal halves. The marks and the crossing make two triangles. Their sides are equal in pairs. So the two halves are equal.
Example: a 62° corner splits into two corners. 62 ÷ 2 = 31, so each is 31°. Bisecting a 90° corner gives 90 ÷ 2 = 45°.
Change the second mark. Watch the two halves.
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