Reciprocal Functions Secant Cosecant Cotangent sec 8 = hypotenuse csc 0 = hypotenuse cot 0 = adjacent adjacent opposite opposite Take another look at these definitions. These functions are the reciprocals of the first three functions. sin 0 = csc 6 = csc 0 sin 0 cos d = 1 sec 0 = sec 0 cos e 1 tan 0 = 1 cot = cot tan 0 Example 10.8: Using the triangle shown in Figure, evaluate sin a, cos a, tan a, sec a, csco, and cota. 4 3 a 5