TI-92 + Cabri Geometry for the Not Necessarily Advanced User

Published on
07/30/2005

Activity Overview

This activity is a tutorial on using the Cabri Geometry™ application. Students' perform geometric constructions which range from simple triangles to complex conics.

Before the Activity

Open the Cabri Geometry application on the TI-92 Plus / Voyage 200 calculator

Use the TI Connect™ and the TI Connectivity Cable to transfer data from the computer to the calculator

See the attached PDF file for detailed instructions for this activity

Print pages 1 - 14 from the attached PDF file for your class

During the Activity

Distribute the pages to the class.

Follow the Activity Procedures:

Drag the ray of a right triangle around the vertex, and observe that it traces a circle

Understand that an angle inscribed in a semi-circle is a right triangle

Understand that the lines joining midpoints of adjacent sides of a quadrilateral form a parallelogram

Construct various quadrilaterals and angle bisectors for each quadrilateral

Construct an equilateral triangle and a point in its interior

Determine the distance of this point to each side

Make a conjecture about the relationship between the sum of these measures and the length of the altitude

Construct a triangle and locate midpoints of two of its sides

Draw an arbitrary point on the third side, and connect it to the midpoints of the other two sides

Make a conjecture about the areas of the resulting quadrilateral and two triangles

Construct a square and the midpoints of two consecutive sides

Plot a point on one of the remaining sides such that the distance from this point to the vertex opposite the chosen sides is one-fourth the length of the side of the square

Form a triangle by joining the three created vertices and hypothesize about the relation between the areas of the triangle and the square

Plot a point inside a circle and a point on the circle

Connect the two points with the help of a segment, and draw a perpendicular bisector to it

Join the point on the circle to the center, and label the point where it intersects the perpendicular bisector

Animate the plot on the circle and observe the traced out ellipse

Explore the ratios of the sides of a right triangle

After the Activity

Students answer the questions on the activity sheet.

Review student results:

As a class, discuss questions that appeared to be more challenging