Trigonometry is unique, in that it spans algebra, basic mathematics, and geometry.
While covering these different topics, it may be relieving to note that trigonometry also quite specific in its duties  it deals with triangles. Of course, if you speak Greek, you already knew this, since Trigonometry combines the Greek words "trigonon" meaning "three angles" (which happens to be a triangle!) and "metro," which you learned in the Geometry lesson, means "measure."
What does that mean? It means, in trigonometry, you will be measuring and calculating the degrees of angles in triangles, along with the length of their sides. There's more to it than just that, but once you are able to do those basic functions, trigonometry will be very easy for you!
Of course, in the course of learning this topics, you'll be introduced to some functions that you'll probably need a scientific calculator to do  these functions are: sine, cosine, and tangent. (On your calculator, those will be named SIN, COS, and TAN.)
So, get your calculator ready (if you haven't already done so), and let's get ready to use it! Continue on to Using Sin, Cos, and Tan or select another topic from the Math Lesson Center.
