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
Re-teach concepts as necessary