Another way to let students explore the relationship between these two angles is a worksheet with a question, so the student gets feedback on his conclusion.

[table][tr][td]step 1       [/td][td][icon]/images/ggb/toolbar/mode_point.png[/icon][/td][td]Select the [i]Point[/i] tool and clik on the circle to create a point C. [/td][/tr][tr][td]step 2[/td][td][icon]/images/ggb/toolbar/mode_segment.png[/icon][/td][td]Select the [i]Segment[/i] tool and click on the points A and C to create a segment.[br]Click on the points B and C to create a second segment.[br][u]Remark[/u]: you can create both segments as well with the commands [i]Segment(AC)[/i] and [i]Segment(BC)[/i].[/td][/tr][tr][td]step 3[/td][td][icon]/images/ggb/toolbar/mode_angle.png[/icon][/td][td]Select the [i]Angle [/i]tool and click respectively on the points A, C and B to create the circumferential angle in C on the given circular arc AB.[/td][/tr][/table][br]Drag the points A, B and C. What do you see?