## 3.22.2011

### SOHCAHTOA Graph Project

Update on my trig ratio graph lesson that I blogged about here. I talked to my pre-calc teacher and he said if I wanted to do this it would be good. So it wasn't necessary and I wasted a lot of time but I still think it was a good lesson. Thanks to @approx_normal for suggesting I test this out on Excel on my own. After some trial and error, I figured out that students would get a good picture of the graph by using multiples of 3 up to 90 degrees. We kept the y window the same, going up to 1 by increments of .1.

I gave them a page with three blank graphs, one for each trig ratio. And then ta-da, I made up another investigation! The hardest part for students was figuring out how to label the graphs. Especially after we realized that the y window for the tangent graph needed to go from 0 to 20 by 2s. (Note: I didn't change that yet so if you use it, that's something you need to look for.)

Then once I got them started on calculating the degrees, it was pretty much smooth sailing. The next stumbling block was when it came to predictions. I had them draw a curve through all the dots.

After using the line to predict certain trig values, I wanted them to use the calculator. But, they just wanted to try it by typing in sin(42). I probably should have shown them how to graph the trig functions on the calculator earlier. But, after they graphed the function, I had them hit trace and type in the necessary angle measure.

To sum things up, I made a Powerpoint with pictures of trig graphs from real life scenarios. The first slide is a graphic organizer which we used to take notes about nonlinear, nonquadratic, discrete, and continuous. I briefly introduced the concept of asymptotes as well.

For homework, students answered the reflection questions on the back about their process. And to be honest, the answers weren't that great. But then again, neither was the assignment.