This activity has the teacher to create 3 triangles on Cabri Jr. on the TI-83 or TI-84. It will prove to students how trigonometry ratios are found. It will show to the students where the ratios are derived rather than just telling the students.
Before the Activity
The teacher needs to follow the directions given on the attachment for "Trig Teacher Handout" to create the triangles and appropriate labels on the calculator. The lesson was designed for the TI-84 but could also be adapted for use on the Voyage or the computer. The students do need to know the basic definitions of trig ratios this just reinforces the idea and shows them how it is applied.
During the Activity
Use the following handout to guide the students thru the lengths of each side of the triangles you have created. You will have to edit the handout so that the angles match the triangles that you have created. Take the students thru each series of questions and try to lead them to each discovery of what the definition really does mean.
After the Activity
You may create more than 3 triangles and do some more comparing lengths. I also hid some of the measures of the sides so that the students found them by hand and then we proved that it was true. I also had more triangles that gave 2 pieces of information and we looked for the other sides or an angle.