Angles in a circle subtended by a chord

The angle made at the centre of a circle by the radii at the end points of a chord is called the central angle or angle subtended by a chord at the centre.

Objectives
Understand different angles subtended by a chord in a circle

Estimated Time
30 minutes

Prerequisites/Instructions, prior preparations, if any
Prior knowledge of point, lines, angles, polygons

Materials/ Resources needed

 * Digital :	Computer, geogebra application, projector.
 * Non digital : Worksheet	and pencil, compass, strings
 * Geogebra	files : Angle	subtended by chord.ggb

Process (How to do the activity)
HW Activity : Draw circle, at the center draw two angles of equal measure. Mark the chords formed by the angles. Measure the lengths of the two chords. Note your observations.
 * Two	equal chords are drawn, the endpoints are joined to the center of	the circle to form triangles.
 * What	can you say of the angles subtended by the two	chords?	How	are the two subtended angles equal. Compare triangles formed.
 * When is the subtended angle the largest?
 * If the angles subtended are equal will the chords be of equal	measure?