Geometry, Teacher\'s Edition

Arc Measures

Pacing:This lesson should take one class period

Goal:This lesson introduces arc measurements. Central angle knowledge is important when creating and interpret-
ing pie charts and when determining arc length and the area of a sector.

Students may need extra practice when it comes to finding the value of the arc. Set up several questions and use
personal whiteboards to check students’ understanding.

The Arc Addition Property should be familiar to students; it is quite similar to the Angle Addition Property.

Additional Example:

Identify the following in

⊙

A

A. Minor arcs

B. Major arcs

C. Semicircles

D. Arcs with equal measurement

E. Identify the four major arcs that contain pointF.

Inscribed Angles

Pacing:This lesson should take one to one and one-half class periods

Goal: This lesson will demonstrate how to find measures of inscribed angles and how to find the measure of an
angle formed by a tangent and a chord.

In-class activity!Have students copy the drawings below.

a. In

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A, use a protractor to find the measures of^6 CDE,^6 CF E,and^6 CBE. Determine the measure of arcCE.

1.9. Circles