Education Technology

# Activities

• ##### Subject Area

• Math: Geometry: Circles
• Math: Geometry: Points, Lines and Angles
• Math: Geometry: Quadrilaterals and Polygons

9-12

45 Minutes

• ##### Device
• TI-Nspire™
• TI-Nspire™ CAS
• ##### Software

TI-Nspire™
TI-Nspire™ CAS

• ##### Other Materials
A detailed instruction sheet, with screen shots is included. A TNS file shows the completed pentagon.

## Constructing a Pentagon, An Alternative Method

#### Activity Overview

Use the TN-Nspire (OS 2.0) to construct a regular pentagon using lines, rays, line segments, and circles of various diameters. The characteristics of a regular pentagon are discussed and used to verify the construction meets the criteria of all sides being equal, and all angles being equal. The measurement feature of the TI-Nspire is used to verify angle measurements, while circles verify sides are congruent.

#### Before the Activity

Download and make copies of word document for teacher and/or students to use. It is detailed enough for students to use for self discovery.

A Video is available, but too large to upload to TI website (8MB) It is available at
http://www.teachertube.com/viewVideo.php?video_id=176582

#### During the Activity

I suggest you use the smaller circle, and line from bottom through left midpoint. Hide to make construction easier and less confusing.

#### After the Activity

Follow through in verifying all the angles are equal, and all sides are equal. Note: to increase decimals for the angle measurement, place cursor on the number (text) and press "+", to decrease, press "-". Also suggest use the settings for "Graphs & Geometry" to change from radians (default) to degrees. Be sure to change for Geometry Angle.