This activity uses Cabri™ Jr. to explore the relationship between inscribed and central angles subtended from the same arc of a circle.

Students require Activity Page

1. Draw a circle in the center of the screen. Label the center O.

Use the point tool to make three points on the circle. Label the points A, B, and C as in Figure 1a.

Construct angle BAC using the Segment tool.

Construct angle BOC using the Segment tool. See Figure 1b.

2. Measure the two angles and using the Angle tool. Record the measurements in the table.

Drag point B along the circle.

Record the new angle measurements in the table.

Continue to drag point B along the circle and record the measurements of the new angles formed.

3. Make a conjecture about the relationship between the measure of an inscribed angle and the central angle subtended by the same arc.

Students complete practice questions on activity page.