For a right triangle △ABC, with the right angle at C and with lengths a, b, and c. For the acute angle A, call the leg BC its opposite side, and call the leg AC its adjacent side. Recall that the hypo...For a right triangle △ABC, with the right angle at C and with lengths a, b, and c. For the acute angle A, call the leg BC its opposite side, and call the leg AC its adjacent side. Recall that the hypotenuse of the triangle is the side AB. The ratios of sides of a right triangle occur often enough in practical applications to warrant their own names, so we can define the six trigonometric functions of A.
