Whenever we are given a point on the terminal ray of an angle, we can calculate all 6 trig values of that angle (without ever knowing, btw, the exact measure of the angle) as follows:
Use pythagorean theorem to calculate r: x2 + y2 = r2 so ... 52 + (-12)2 = r2 and r = 13
Use coordinate plane definitions of the trig ratios:
sinΘ = y/r ; cscΘ = r/y so sinΘ = - 12/13 and cscΘ = - 13/12
cosΘ = x/r ; secΘ = r/x. so cosΘ = 5/13 and secΘ = 13/5
tanΘ = y/x ; cotΘ = x/y so tanΘ = - 12/5 and cotΘ = - 5/12
Finally, cotΘ·secΘ + sinΘ = (-5/12)(13/5) + (-12/13) = -13/12 - 12/13 = - 313/156