# Trigonometric Ratio: Secant

How to solve secant (trigonometric ratio) problems: definition, example, and its solution.

## Definition

Secant is the reciprocal of cosine.

Cosine: CAH.

[cos *A* = (**A**djacent side) / (**H**ypotenuse)]

So sec *A* = (**H**ypotenuse) / (**A**djacent side).

## Example

sec *A* = (hypotenuse) / (adjacent side)

In the given right triangle,

the hypotenuse is missing.

So find the hypotenuse

by using the Pythagorean theorem.

(hypotenuse) = √5

sec *A* = 1 / cos *A*

Cosine: CAH.

So cos *A* = 1/√5.

So, its reciprocal, secant is

sec *A* = √5/1.