# SEC function

## Description

Secant function. SEC(x) returns the secant of x. The argument x must be expressed in radians. To convert degrees to radians you use the RADIANS function.

The secant is the reciprocal of the cosine:

$$ \operatorname{sec}(x) = \frac{1}{\operatorname{cos}(x)} $$

The argument x can be a real number or a matrix. When it is a matrix, the function returns a matrix with the same dimensions and with the SEC function applied to all elements.

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## Recommended book

## Trigonometry: A Complete Introduction

Hugh Neill

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This book covers all areas of trigonometry including the theory and equations of tangent, sine and cosine, using trigonometry in three dimensions and for angles for any magnitude, related to triangles. Everything you will need is here in this one book. Each chapter includes not only an explanation of the knowledge and skills you need, but also worked examples and test questions.