Basing on a triangle to get the opposite side you'll have
cos α = 1/4
where 1 is the measurement of the adjacent side and 4 is the hypotenuse
opposite side = √(4²-1²)
opposite side = √15
take note that that the angle is located in between 270 and 360 degrees therefore its x is positive and y is negative..
sin α = -√15/4
tan α = -√15 / 1
tan α = -√15
sec α = 4/1
sec α = 4
csc α = 4/-√15
csc α = -4/√15
cot α = 1/-√15
cot α = -1/√15
