Education Technology

Mathematics lessons for IB® Diploma Programme

Applications and Interpretation | Geometry and Trigonometry


Circles: Angles and Arcs

Activity Overview

Students explore angles constructed in a circle and how their measures are related to the measures of the intercepted arcs.

Key Steps


Step 1

In Problem 1, students explore inscribed and central angles using Cabri™ Jr. They will see a central angle AOB has been constructed and measured. The central angle measure is used as the arc measure.

Students construct a point labeled C and construct two segments AC and BC.


Step 2

They will realize that the measure of the arc is twice that of the measure of angle ACB.