In a right angled triangle, the secant of an angle is:

The length of the hypotenuse divided by the length of the adjacent side.

The abbreviation is sec

Example: in a triangle with sides of 3, 4 and 5, the secant of the angle where the sides of length 4 and 5 meet is 5/4

It is not commonly used, and is equal to 1/cosine

The length of the hypotenuse divided by the length of the adjacent side.

The abbreviation is sec

Example: in a triangle with sides of 3, 4 and 5, the secant of the angle where the sides of length 4 and 5 meet is 5/4

It is not commonly used, and is equal to 1/cosine