Soh-Cah-Toa and Trigonometry Functions


When I was in Trig class, my teacher told us that the single most important figure in the history of Trigonometry was not some mathematician like Blaise Pascal or RenĂ© DeCartes, but a mythical American Indian chief named Soh-cah-toa. This man’s history and accomplishments are clouded by time, but over the years he has single-handedly helped countless Trigonometry students memorize the formulas for angle functions in a right triangle.

So how did he accomplish this feat, you may ask? Chief Soh-cah-toa’s name is a mnemonic device that will help you remember how to find the sine, cosine, and tangent in a right triangle. Here’s how it works:


– This is short for Sine equals Opposite side over Hypotenuse. (If you recall, the Opposite side is the side of the triangle directly opposite the angle you’re examining. The hypotenuse is the longest side, the one opposite the right angle.)


– This is short for Cosine equals Adjacent side over Hypotenuse. (The Adjacent side is the side of the triangle next to the angle you’re examining that is NOT the hypotenuse.)


– This is short for the Tangent equals the Opposite side over the Adjacent side. (You’ll notice this one doesn’t even need the hypotenuse!)

Chief Soh-cah-toa has helped countless trigonometry students remember basic trig functions. Know his name, and he will help you remember them too.