How do you evaluate #sec110°#?
1 Answer
Sep 26, 2015
Find
Ans: -2.94
Explanation:
Call cos (110) = cos x
Use the formula:
cos 330 = cos (-30 + 360) = cos 30 = sqrt3/2
Solve this cubic equation by graphing calculator
By estimation, we get;
cos x = - 0.34 --> x = 110 (accepted) --> 3x = 330
cos x = - 0.65 --> x = 130 (rejected) --> 3x = 390
cos x = 0.98 --> x = 10 (rejected) --> 3x = 30
Finally:
graph{4x^3 - 3x - sqrt3/2 [-2.5, 2.5, -1.25, 1.25]}