Tuesday, November 6, 2012

Trigonometry - Learning to Graph Sine & Cosine

In trigonometry, we've begun our Trig unit. Of course, we did our unit plate (here's the link to this lesson) but this time, I did it slightly differently. I'm hoping to post about that at a later time.

After grilling on this for a bit, it was time to dive into graphing! (We have a week long break for Thanksgiving so we discussed why we should test before break and not after).

I started out by having the kids fill out the x/y table for the positive radians of cosine. Of course, I did the first three with them and then set them free. Next, I walked them through the negative radians referring to my unit circle plate and going around the circle with a pen. This helped them fill out the first two and then again, I set them free! I started to hear, "THEY"RE THE SAME!" and of course they started to get all excited. After confirming this fact and creating proper x/y tables, I had the kids graph the coordinates and connect the dots. We then analyzed the domain/range/period/symmetry for cosine.

We repeated this process for sine and examined the differences between the two (because of their symmetry). The kids loved to see the patterns and things were starting to click. Now of course, this was difficult if the kids didn't know the unit circle as they had no idea where the values were coming from. Their homework for the night was a discovery worksheet where they looked at the various translations of a trigonometric graph (amplitude/period/phase/vertical shifts).

Tomorrow, we begin looking at them all happening at once... but together :)
Learning to Graph Sine & Cosine