John R. answered 03/12/23
Calculus, Probability, and Stat Tutor, Math Degree, 20+ years Exp.
The normal period of sec x is 2*pi. The 12 in front of the x will make the function run through its values 12 times faster, so the new period will be 1/12th of 2*pi. More generally, a horizontal scaling by a factor of k is accomplished by replacing x with x/k. To get from sec x to sec 12x we must replace x with x / (1/12) = 12x, so the horizontal scale factor is 1/12. (Some texts may say, we shrunk it by a factor of 12, but this can be a little misleading, or ambiguous.)
Note that sec x = 1 / cos x has a vertical asymptote wherever cos x = 0, or at every odd multiple of pi / 2. Thus, applying the scale factor of k = 1 / 12, the graph of sec 12x will have vertical asymptotes at every odd multiple of
pi / 2 * 1 / 12 = pi / 24.