? 57158 J Comment. 7. 57185. 57185 - 10. 57158. EXAMPLE 3. 43254 - 10. Find the acute angle a by use of the five-place 17. 19. 21. 23. 25. 27. log log log log log log tan sin cot tan tan sin a a a a a a 18. Hence, as below, we find that a is 24/45 of the way from 74° 17' to 74° 18'. 5, to nearest tenth. 5'. 5'. 47. Accuracy of certain results If the logarithm of some function of an unknown angle a is given, we find a by use of the four-place Table VI or five-place Table IX according as the given logarithm is specified to four or to five decimal places, respectively.

Xl - Y Similarly, we may show that [any function of (270° + 0)J = 62. Reduction formulas for (90° - Al Xl 0 X FIG. 49 ::I:: 0), (180° - (cofunction of 0). 0), and (270° - 0) By use of the formulas for functions of (- () on page 71, we can obtain the following identities involving (90° - (), (180° - (), (270° - () from those for (90° + (), (180° + (), (270° + (), respectively. csc (90° - 0) = sec 0; sec (90° - 0) = csc 0; tan (90° - 0) = cot 0; cot (90° - 0) = tan 0. [Any function of (180° - O)J = ::f:: (same function of 0).