In a right triangle, the hypotenuse is the longest side, an "opposite" side is the one across from a given angle, and an "adjacent" side is next to a given angle. This link will take you to the entire course by Khan Academy on trig ratios. It includes articles, videos, and areas for students to practice what they have learned.

trigonometry math tangent sine cosine Sin gr. 10 right-angled triangles soh cah toa trigonometric ratios cos tan