How secant is defined
Secant is the reciprocal of cosine: sec(θ) = 1/cos(θ). It is undefined wherever cosine equals zero — at odd multiples of 90° (90°, 270°, ...).
Like cosecant, secant values are always outside the interval (-1, 1).
Secant Calculator
Calculate the secant (1/cos) of an angle in degrees or radians with undefined-angle detection at 90 and 270 degrees.
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Trigonometry
Secant of an angle with undefined-angle detection
The secant calculator computes sec(θ) = 1/cos(θ) for any angle. It detects undefined values at 90°, 270°, and other angles where cosine is zero.
Exact values
Common exact values: sec(0°) = 1, sec(30°) = 2sqrt(3)/3, sec(45°) = sqrt(2), sec(60°) = 2.
Frequently asked questions
1. cos(0°) = 1, so sec(0°) = 1/1 = 1.
Because cos(90°) = 0 and secant is 1/cos. Division by zero is undefined.
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Calculate the cotangent of an angle in degrees or radians with undefined-angle detection where sine is zero.
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Calculate the arccosine (inverse cosine) of a value and return the angle in degrees and radians with exact fractions of pi.
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