Get the help you or your students need remembering all of the formulas needed for right triangle trigonometry problems with this handy right triangle trig formula sheet.

# Triangles

This two-page set of notes has students compare two methods of finding the distance between two points on the coordinate plane: the pythagorean theorem and the distance formula. It is designed for Pre-Calculus students who have seen both methods taught in previous courses. In my many years of teaching pre-calculus, I have found that students …

It will be a few years before we get to celebrate the next Pythagorean Theorem Day in July of 2025. Here are some ideas for celebrating this fun mathematical holiday. For many, the Pythagorean theorem (also known as Pythagoras’ theorem) is one of the most memorable formulas from high school math. Most adults would likely …

I use these classifying triangles by angles and sides notes with my pre-calculus students as part of our first unit of the year which covers mainly geometry review. Especially with the pandemic, I have to spend quite a bit of time reviewing geometry before we can jump properly into trigonometry. I have my students fill …

Sankaku puzzles are a geometric based logic puzzle that focuses on finding the area of a triangle. The goal of each puzzle is to connect three dots to form a triangle with the specified area. Sankaku puzzles are the creation of Naoki Inaba, a prolific Japanese puzzle creator. I first discovered these puzzles several years …

This tricky triangles puzzle has been around for over a century – can you arrange these eight sticks to form exactly four triangles and two squares? The original puzzle was meant to be solved with matchsticks, but I don’t think I need to explain why I won’t be giving my students matchsticks to play with… …

It’s November which means it’s finally time to pull out this Triangular Turkey puzzle for Thanksgiving. How many different triangles can you find in this picture of a Thanksgiving turkey? I ran across this triangular turkey puzzle in a Martin Gardner book (Perplexing Puzzles and Tantalizing Teasers) this summer, and I knew I had to …

I’m excited to get back to featuring a new puzzle of the week every week in my classroom this year. A new puzzle I have prepped for this year is called Three of Five. Three of these five figures fit together to create a triangle. Which ones are they? I ran across this puzzle in …

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 …

Looking for a challenge? Check out this page of Make It Pythagorean Puzzles. Insert the same digit (in any manner of your choosing) to each side of the triangle to form a right triangle. I ran across these interesting puzzles in Golf on the Moon by Dick Hess (Dover Publications).

The Parts of a Whole Puzzle gives students five shapes that must be arranged to form a triangle whose three sides are of equal length. In other words, form an equilateral triangle. I would have renamed this as the Equilateral Triangle Puzzle, but I have already shared a different equilateral triangle puzzle on my blog …

I am really excited about this shape grid puzzle from Erich Friedman. The goal of the puzzle is to divide the grid into geometric shapes. Any lines you draw must follow either the grid lines or the diagonals of the grid squares. Each shape that you draw must contain exactly one shape icon inside. This …

I created these trig functions posters a few years ago when I was teaching a year-long trigonometry course. Somehow, they never got a blog post of their own. I created separate posters for the three basic trig functions and the three reciprocal trig functions. I designed these posters to print on 11 x 17 cardstock. …

I created this Parts of a Right Triangle poster several years ago when I was teaching trigonometry. I wanted to emphasize the vocabulary words for adjacent, opposite, and hypotenuse before we jumped into right triangle trig. I designed this parts of a right triangle poster to print on 11 x 17 cardstock. I hung this …

I want to share a pythagorean theorem poster I created several years ago for my classroom when I was teaching trigonometry. I designed this poster to print on 11 x 17 cardstock. I hung this poster on a bulletin board in my classroom with several other 11 x 17 posters I created. As I continue …

This equilateral triangle puzzle comes from Puzzle Box, Volume 1 from Dover Publications. This is the first book in a series of three puzzle books that are edited by the Peter and Serhiy Grabarchuk. This specific puzzle is by Richard Candy. Each volume has 300 puzzles, and I have found over a hundred puzzles between …

Zukei puzzles are the brilliant creation of Naoki Inaba. Inaba has posted these puzzles for free on his website, but it can be a bit hard to navigate since everything is written in Japanese. You may have heard of Inaba from his popular area maze puzzles. Instructions for Solving Zukei Puzzles The instructions for the …

I love this clinometer activity for giving my trigonometry students extra practice finding missing angles and sides of right triangles. Plus, it answers the question of “When will we ever use this?” I printed a clinometer template off of VirtualMaths.org for them to use. I mistakenly assumed that they would be able to put together …

I created this finding missing angles of right triangles practice book for my trigonometry students to glue in their interactive notebooks. My students were a bit miffed that they had to just write these equations. They thought I should have given them a foldable for these! I did make them a practice book, though. These …

We created this parts of a right triangle interactive notebook page to start off our unit on right triangle trigonometry. Each student had to cut a right triangle out of colored paper and glue it into their notebooks. We labeled one of the non-90 degree angles as theta. Then, we discussed how to identify the …

To give my students a bit more practice with word problems, I typed up these Romeo and Juliet themed pythagorean theorem problems. These are slightly modified from this Weebly site. Free Download of Romeo and Juliet Pythagorean Theorem Questions

I decided my students needed a Pythagorean Triples reference page in their notebooks to go along with the posters I have hanging in my classroom. Here is the page. You will notice that 6, 8, 10 is not included on the list because it is related to 3, 4, 5. Free Download of Pythagorean …

I gave this missing angles task to my Trigonometry students as part of our beginning of year algebra and geometry review. I had students find the missing angles in this diagram that I found online. Here’s a link the original source. Free Download of Missing Angles Task

I created this interactive notebook page to help illustrate the sum of angles in a triangle. Instead of just telling my students that the sum of the angles in a triangle is always 180 degrees (something I hope they remember from geometry!), I decided to have them cut out a triangle and illustrate it themselves. …

I created this practice book to give my trigonometry students some much needed review of finding the distance between any two points on the coordinate plane. I’m a rebel and chose not to teach the distance formula since it’s way easier to just use the Pythagorean Theorem instead. Instructions for Finding the Distance Between Any …