The value of arc sec of any number is equal to an angle in unit degrees or radians. In this case, sec is the inverse of cos, so as we input in the calculator, we write (1/cos)^-1 (2) or simply (cos)^-1 (0.5). The answer is pi/ 3. cosine of an angle located in the first and fourth quadrant is positive . Hence the answer that is applicable is b. pi/3/
