OpenOlympiad
Concept 5 of 10Foundation
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Angle bisector

An angle bisector is a ray that splits an angle into two equal halves.

Construction of bisector of ∠BAC:

  1. From vertex A, draw an arc crossing both arms at P and Q.
  2. From P and Q (same radius), draw arcs meeting inside at R.
  3. Ray AR bisects ∠BAC.

Every point on the bisector is equidistant from the two arms.

Example
The 3 angle bisectors of a triangle meet at the incentre — centre of the largest circle that fits inside.
💡 Tip:You can make 60°, 30°, 15° angles just with a compass by bisecting repeatedly.
Prefer a video? Open YouTube search for “angle bisector construction class 6

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5 questions to check what you just read.

0 / 5
  1. Q1.An angle bisector splits an angle into:
  2. Q2.Bisector of a 60° angle creates two angles of:
  3. Q3.Bisector of a 180° straight angle creates:
  4. Q4.Three angle bisectors of a triangle meet at the:
  5. Q5.Any point on an angle bisector is equidistant from: