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Angle Bisectors and Incircle

Geometry and Measures Angle Bisectors and Incircle

🎬 Video Tutorial

(0:01) Angle Bisector: A line or ray that divides an angle into two equal parts. For example, if the angle is $60^\circ$, the angle bisector will split it into two angles of $30^\circ$ each.
(0:40) Constructing Bisectors with a Compass: Draw an arc from the vertex to create intersection points. Then, without changing the compass width, draw additional arcs from each point to find the bisector.
(1:26) Incentre of a Triangle: The incentre is the intersection of the triangle’s angle bisectors, equidistant from all three sides.
(1:50) Inradius and Incircle: The distance from the incentre to any triangle side is the inradius. Use the incentre and inradius to draw the incircle, touching all sides.

📂 Revision Cards

Angle bisector dividing an angle into two equal parts, with one half labelled ?/2 and the other half also labelled ?/2.

Constructing an angle bisector using a protractor and compass, showing steps for accurate measurement and drawing.

Key property of angle bisectors shown with diagram: every point on the angle bisector is equidistant from the angle's sides.

Explanation of a triangle's in-centre and in-circle, showing the largest circle that can fit inside the triangle, with in-radius and angle bisectors.

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