Question 933006
May subtract multiples of 2pi for the desire value
4pi = 16pi/4  Re TY: {{{16pi/4  = (16/4)pi = 4pi}}}
sec(19pi/4 - 16pi/4) = sec(3pi/4) = -2/√2  = -√2/2
............
(cosx, sinx) Summary Unit Circle
*[illustration wheel_smaller.jpg].