Secant Calculator — sec(θ) with Full Trig Breakdown

Calculate sec(θ) = 1/cos(θ) in degrees, radians, or gradians. All 6 trig functions, identity verification, asymptote warnings, sign chart, and common values.

sec(θ)
2.000000
1 / cos(60.00°) = 1 / 0.500000
cos(θ)
0.500000
The reciprocal of sec(θ)
sin(θ)
0.866025
sin(60.00°)
tan(θ)
1.732051
sin(θ) / cos(θ)
Quadrant
Q1
sec is positive in Q1
Angle (degrees)
60.000000°
= 1.047198 rad = 66.666667 grad

All Six Trig Functions & Reciprocals

csc(θ)
1.154701
1 / sin(θ)
cot(θ)
0.577350
cos(θ) / sin(θ)
sec²(θ)
4.000000
Should equal 1 + tan²(θ)
1 + tan²(θ)
4.000000
Pythagorean identity verification

Quadrant Sign Chart for sec(θ)

Q II
(−)
Q I
(+)
Q III
(−)
Q IV
(+)

sec(θ) = 1/cos(θ) shares the same sign as cos(θ): positive in Q I & Q IV, negative in Q II & Q III.

Key Secant Identities

IdentityFormulaVerified Value
Definitionsec θ = 1 / cos θ2.000000
Pythagoreansec² θ = 1 + tan² θ4.000000 ≈ 4.000000
Even functionsec(−θ) = sec θsec is even (symmetric about y-axis)
Periodsec(θ + 360°) = sec θPeriod = 360° = 2π
Cofunctionsec θ = csc(90° − θ)1.154701
Rangesec θ ∈ (−∞, −1] ∪ [1, ∞)✓ in range

Common sec(θ) Values

Anglesec(θ) exactsec(θ) decimalcos(θ)
11.00001.0000
30°2/√3 ≈ 1.15471.15470.8660
45°√2 ≈ 1.41421.41420.7071
60°22.00000.5000
90°UndefinedUndefined0.0000
120°−2-2.0000-0.5000
135°−√2 ≈ −1.4142-1.4142-0.7071
150°−2/√3 ≈ −1.1547-1.1547-0.8660
180°−1-1.0000-1.0000
210°−2/√3 ≈ −1.1547-1.1547-0.8660
225°−√2 ≈ −1.4142-1.4142-0.7071
240°−2-2.0000-0.5000
270°UndefinedUndefined-0.0000
300°22.00000.5000
315°√2 ≈ 1.41421.41420.7071
330°2/√3 ≈ 1.15471.15470.8660
360°11.00001.0000

Domain Restrictions

Asymptote (°)Asymptote (rad)Reason
-270°-4.7124 radcos(-270°) = 0
-90°-1.5708 radcos(-90°) = 0
90°1.5708 radcos(90°) = 0
270°4.7124 radcos(270°) = 0
450°7.8540 radcos(450°) = 0
General: θ = 90° + 180°·n for any integer n ⟹ cos θ = 0 ⟹ sec θ undefined
Planning notes, formulas, and examples

About the Secant Calculator — sec(θ) with Full Trig Breakdown

The **Secant Calculator** evaluates sec(θ) = 1/cos(θ) for any angle in degrees, radians, or gradians. It provides a complete trigonometric breakdown: all six standard functions (sin, cos, tan, cot, sec, csc) are computed simultaneously, and the Pythagorean identity sec²θ = 1 + tan²θ is verified numerically to confirm consistency.

When the input angle is an odd multiple of 90° — where cos(θ) = 0 — the calculator displays a clear asymptote warning instead of producing misleading results. A quadrant-sign visual grid shows at a glance where sec is positive (Quadrants I and IV) and where it is negative (Quadrants II and III), with the current quadrant highlighted.

A key identities table lists six fundamental secant relationships, each verified with the current angle's computed values. The common-values table covers 17 standard angles from 0° to 360° in 30° and 45° steps, showing both the exact algebraic form and the decimal approximation. The closest match to the current input is highlighted for quick cross-referencing.

A dedicated domain-restrictions table lists the vertical asymptotes of sec(θ) around the input, along with the general rule θ = 90° + 180°n. Eight preset buttons cover the most common angles. Adjustable precision from 0 to 12 decimal places and toggles for the reciprocal-functions section and identities section let you customize the output to your needs.

When This Page Helps

Secant Calculator — sec(θ) with Full Trig Breakdown helps you avoid repetitive setup mistakes when solving trigonometric and coordinate-geometry problems. Instead of recalculating conversions, signs, and edge cases by hand, you can test inputs immediately, inspect intermediate values, and confirm final answers before submitting work or using numbers in downstream calculations. It surfaces key outputs like sec(θ), cos(θ), sin(θ) in one pass.

How to Use the Inputs

  1. Enter the required inputs (Angle (θ), Unit, Decimal Precision).
  2. Complete the remaining fields such as Show Reciprocal Functions, Show Identities.
  3. Review the output cards, especially sec(θ), cos(θ), sin(θ), tan(θ).
  4. Compare the result with the formula, diagram, or example values to catch sign, unit, or rounding mistakes.
Formula used
sec(θ) = 1/cos(θ). Undefined when cos(θ) = 0 (at θ = 90° + 180°n). sec²θ = 1 + tan²θ (Pythagorean identity). sec(−θ) = sec(θ) (even function). Period = 360° = 2π.

Example Calculation

Result: sec(60°) = 2, cos(60°) = 0.5, sin(60°) ≈ 0.8660, tan(60°) ≈ 1.7321

Using θ=60°, the calculator returns sec(60°) = 2, cos(60°) = 0.5, sin(60°) ≈ 0.8660, tan(60°) ≈ 1.7321. This example mirrors the calculator's live computation flow and is useful for checking manual steps and unit handling.

Tips & Best Practices

  • sec(θ) shares the same sign as cos(θ) in every quadrant — positive in Q I and Q IV.
  • The range of sec is (−∞, −1] ∪ [1, ∞) — it is never between −1 and 1.
  • Secant is an even function: sec(−θ) = sec(θ), just like cosine.
  • Vertical asymptotes occur at every odd multiple of 90° (or π/2 radians).
  • In calculus, the derivative of sec(θ) is sec(θ)·tan(θ).

What This Secant Calculator — sec(θ) with Full Trig Breakdown Solves

This calculator is tailored to secant calculator — sec(θ) with full trig breakdown workflows, including common input modes, unit handling, and special-case behavior. It is designed for fast checking during homework, exam preparation, technical drafting, and coding tasks where trigonometric consistency matters.

How To Interpret The Outputs

Use the primary result together with supporting outputs to verify direction, magnitude, and validity. Cross-check against known identities or geometric constraints, and confirm that angle ranges, sign conventions, and domain restrictions are satisfied before using the numbers elsewhere.

Study And Practice Strategy

A reliable way to improve is to solve once manually, then verify with the calculator and explain any mismatch. Repeat this on varied examples and edge cases. The built-in preset scenarios for quick trials, comparison tables for side-by-side validation, visual cues that make trends and quadrants easier to read help you build pattern recognition and reduce sign or conversion errors over time.

Sources & Methodology

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Frequently Asked Questions

  • Secant (sec) is the reciprocal of cosine: sec(θ) = 1/cos(θ). It is one of the six standard trigonometric functions and appears frequently in calculus, physics, and engineering.