Education Technology

Cabri Jr. Inscribed and Central Angles

Activity Overview

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

Before the Activity

Students require Activity Page

During the Activity

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.

    After the Activity

    Students complete practice questions on activity page.