Secant Calculator
Calculate sec(θ), the reciprocal of cosine, for a signed angle in degrees. Angles 90° + 180°k are undefined.
Formula
sec(θ)=1/cos(θ); cosine uses θπ/180 radians. Undefined at θ=90°+180°k, k integer.
Secant (unitless) ≈ 1÷(cos(((60)-360×round((60)÷360))×pi÷180)×min(1,ceil(abs((60)-90-180×round(((60)-90)÷180)))))
How to use
- Enter the angle in degrees.
- Use a minus sign for clockwise rotation.
- Read the unitless secant; undefined angles return an error.
Examples
- sec(60°)=2 and sec(120°)=−2.
Frequently asked questions
Is secant the same as arccos?
No. Secant is 1/cos(θ); arccos finds an angle from a cosine value.
What happens at 90°?
Cosine is zero, so no finite secant exists. All exact odd multiples of 90° are rejected.
Does a negative angle change the result?
Secant is even: sec(−θ)=sec(θ) wherever defined.
Sources
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