Secant is a trigonometric function that quantifies the quotient of hypotenuse and the side that is adjacent to the given angle. This is the reciprocal of the cosine function.
cosine = adjacent / hypotenuse = x/h
secant = h / x
Secant equal to -1 means that x and h are numerically equal but opposite in sign.
secant = -1
cosine = 1/secant =1/-1 = -1
arccos (-1) = 180°
Thus, the answer to this item is 180°.