Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Circles
• Math: Geometry: Reasoning
• Math: Geometry: Triangles

9-12

45 Minutes

• ##### Device
• TI-Nspire™ CX/CX II
• TI-Nspire™ CX CAS/CX II CAS
• TI-Nspire™
• TI-Nspire™ CAS
• ##### Software

TI-Nspire™
TI-Nspire™ CAS

2.1

## Cell Phone Towers

#### Activity Overview

In this activity students explore the locus of a point that is located twice as far from a given point A as it is from given point B. The locus is Apollonius circle. Students discover that the locus is a circle and then prove it. The key property: If a ray bisects an angle of a triangle, then it divides the opposite side into segments whose lengths are proportional to the lengths of the other two sides.

#### Before the Activity

Before carrying out this activity teacher should review with the students the concepts of angular bisector, internal and external angles of polygons, and the equation of a circle.

#### During the Activity

The Word document is a teacher file that the teacher should use to facilitate this activity in class. The student .tns file can be used by students to follow along in this teacher-led activity.