Sankaku Puzzles

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 ago on Inaba’s website (which is written entirely in Japanese), and I featured them in a round-up on my blog of Japanese Logic Puzzles for the Secondary Math Classroom.

I recently ran across them again, and I decided that they deserved their own entire blog post to hopefully help them get the attention they deserve. These puzzles should be of special interest to geometry teachers or anyone who includes teaching about finding the area of triangles in their curriculum.

Inaba includes 42 of these triangle-finding puzzles on his website. They are spread over eight pages which I find really hard to print and use in my math classroom as-is.

I decided to compile the puzzles into a Word document so that they only take four pages instead of the original eight. I also added my English translation of the original Japanese instructions.

I printed these four pages in booklet mode to make a mini puzzle book of the sankaku puzzles for my students.

As you can see inside the booklet, the puzzles start out on 3 x 3 grids, but they quickly increase in difficulty to 4 x 4 grids.

I hope you and your students enjoy hunting for triangles as you solve these sankaku puzzles!

If you like these puzzles, I highly suggest you check out Naoki Inaba’s other math-based logic puzzles. His Zukei Puzzles are another great puzzle for geometry teachers!