# Activities

• • • ##### Subject Area

• Math: Math General: General

• ##### Author 9-12

60 Minutes

• ##### Device
• TI-92 Plus / Voyage™ 200

TI Connect™

• ##### Accessories

TI Connectivity Cable

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

#### 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.

• 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 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
• Re-teach concepts as necessary