I created these SOH CAH TOA notes for my Pre-Calculus students a few years ago to review how to find the trigonometric functions of an angle, given a triangle.

First, we reviewed the different parts of a right triangle. I have also created a poster of the parts of a right triangle that might be of interest. We discussed that the hypotenuse of a right triangle is always the same, but the opposite and adjacent sides are dependent on the placement of theta which marks the angle we are interested in.

Next, we reviewed SOH CAH TOA and used the mnemonic to write the formulas for finding sine, cosine, and tangent. I used this as an opportunity to do some purposeful color coding.

This should have been a review for my students from geometry class, but I have had some students skip geometry. They have taken Algebra 1, Algebra 2, and Pre-Calculus with no geometry in between. For these students, this is a completely new concept.

In the next few years, reviewing the basic trig functions with my pre-calculus classes will be even more important since some of them will have missed that part of geometry due to the pandemic. When Oklahoma shut down schools in 2020, we were told to not teach any new content – just provide enrichment. As a result, my school’s geometry classes did not cover any trigonometry in 2020.

Finally, I introduced my students to the reciprocal trig functions. Cosecant, secant, and cotangent are first introduced in Pre-Calculus in Oklahoma.

On the back of our notes page, we practiced finding the six trig functions for three different triangles.

If you would like to modify these notes to use them in your own classroom, I have uploaded them below.

## Free Download of SOH CAH TOA Notes

SOH CAH TOA Notes (WORD) (560 downloads)

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- 5 Free Printable Trigonometry Posters
- Unit Circle Bingo Game
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- SOH CAH TOA Notes
- Let’s Make Squares Activity
- Make It Pythagorean Puzzles
- 1932 Geometry Lesson
- Parts of a Whole – An Equilateral Triangle Puzzle

Jill Hardy

Tuesday 20th of July 2021

The first year I taught SOH CAH TOA, I pointed out how lucky we were to live in Southern California (SO CA) and our city starts with H. One girl blurted out, “And my sister goes to school in Tulsa, Oklahoma, America!” I still teach all 3 acronyms that way ?