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# Discovering Trig

Lesson 1 of 4

## Objective: Students will be able to identify sine, cosine and tangent ratios using three similar triangles.

#### Do Now

*10 min*

For this lesson Do Now, students review finding right triangle side lengths using the Pythagorean theorem. Activating this prior knowledge will prepare students to persevere through a challenging discovery similar triangle centered activity as they engaging in repeated reasoning to determine the sine, cosine and tangent trigonometric ratios (MP 1 and MP 8). The CCSS Geometry curriculum only focuses on right triangle trigonometry so this unit might be well placed after a similar triangle and/or shapes unit.

#### Resources

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#### Getting Triggy with It

*5 min*

In order to get students excited about the start of this trigonometry unit, teachers can show this video. The video highlights some important topics that will be studied in this unit, like sine, cosine and tangent. The video shows a high school in Ohio re-creating the Will Smith song to "Getting Triggy with It." You can find a copy of the Lyrics for Getting Triggy with It for students here.

#### Resources

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Students may still need time to finish the activity at the end of class but if time remains, they can start the Homework - Discovering Trig which includes review questions from the Regent's Prep website that focuses on similar triangles.

Students can complete question #1 from the homework assignment, as an exit ticket. The question has students write an email to a classmate who is absent, explaining how we discovered sine, cosine and tangent using similar triangles.

#### Resources

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*From where I'm looking at the activity, the page doesn't look big enough to draw triangles of that size on the grid. Is this enough room? | 8 months ago | Reply*

I loved the video "Get triggy with it". i also used the activity to introduce the trig lesson.

| one year ago | Reply

Nice activity. I am planning to start the year out with right triangle trig and will jump right into this activity after reviewing similarity so that students will be able to do the Regents homework as well. I think I will use Deana's idea of nesting the triangles on one larger sheet. Handout has small error -- there are 3 right triangles, not 4.

| 2 years ago | Reply

Good, easy to follow lesson that I use and get great results with-- I do however, have them make 3 nested triangles on the larger sheet instead of three separate sheets! Works every time.

The videos are great!

| 2 years ago | Reply

Hi Erin-Rose,

Yes, I love all those videos and show them whenever possible. They are awesome! Thanks for sharing :)

| 3 years ago | Reply

I love love love Gettin' Triggy Wit it. I have used it for the past 3 years in my classroom. Have you watched any of their others? I also use Graph!! and All I do it Solve as reminders when do a quick Algebra review in the beginning of the year.

| 3 years ago | Reply

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- UNIT 1: Introduction to Geometry: Points, Lines, Planes, and Angles
- UNIT 2: Line-sanity!
- UNIT 3: Transformers and Transformations
- UNIT 4: Tremendous Triangles
- UNIT 5: Three Triangle Topics
- UNIT 6: Pretty Polygons
- UNIT 7: MidTerm Materials
- UNIT 8: Circles
- UNIT 9: 3-D Shapes and Volume
- UNIT 10: Sweet Similar Shapes
- UNIT 11: Trig Trickery
- UNIT 12: Finally Finals