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SEC Function

Excel 2007+

Summary

The Excel SEC function calculates the secant of a given angle in radians, providing essential trigonometric functionality for mathematical computations and engineering analysis.

Syntax

SEC(number)

Parameters

Parameter	Type	Required	Description
number	`Number`	Yes	The angle (in radians) whose secant value you want to find. Absolute value must be less than 2^27.

Using the SEC Function

SEC is a fundamental trigonometric function used in mathematics, physics, and engineering calculations. Convert degrees to radians using RADIANS or PI()/180 for degree-based inputs.

Common SEC Examples

Secant of 45 Degrees

=SEC(45*PI()/180)

Calculates secant of 45° angle (approximately 1.90359)

Secant of 30 Degrees

=SEC(30*PI()/180)

Calculates secant of 30° angle (approximately 6.48292)

Using RADIANS Function

=SEC(RADIANS(45))

Converts 45 degrees to radians then calculates secant

Frequently Asked Questions

Multiply degrees by PI()/180 or use =SEC(RADIANS(degrees))

SEC returns #NUM! error value

Non-numeric inputs return #VALUE! error

Common Errors and Solutions

#NUM!

Cause: Angle absolute value ≥ 2^27

Solution: Ensure |number| < 2^27

#VALUE!

Cause: Non-numeric input

Solution: Provide valid numeric angle

#DIV/0!

Cause: Angle where cos(number) = 0 (odd multiples of π/2)

Solution: Check angle validity

Notes

SEC(number) = 1/COS(number)
Maximum angle: ±2^27 radians
For degrees: SEC(degrees*PI()/180)
Related to hyperbolic secant via SECH function

Compatibility

Available in: Excel 2007+, Excel 2010+, Excel 2013+, Excel 2016+, Excel 2019+, Excel 365+

Not available in:

Content last reviewed: December 11, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+