sin, cos, tan, cot, sec, and csc
Note: Problems 2.15–2.19 refer to the right triangle in the diagram below.
2.15 Identify one leg that is adjacent to, and one leg that is opposite, angle α.
Trigonometric ratios (like sine, cosine, and tangent) are defined in terms of the relationship between the acute angles of a right triangle and the lengths of the sides of that right triangle. Therefore, you need to know how to describe the legs of a right triangle as either “opposite” or “adjacent to” an acute angle.
Acute angles measure less than 90°, so the acute angles of a right triangle are the two angles that aren’t right ...