CommandssecOn this pagesec sec (angle) The sec function returns the secant of angle which is in radians: sec(x)=1cos(x).\displaystyle \sec (x)=\frac{1}{\cos (x)}.sec(x)=cos(x)1. In complex expressions, angle is complex, and sec(angle) returns a complex value. See Also sin, cos, tan, csc, cot