Secant Calculator

This secant calculator works out the secant of any angle you enter, in degrees or radians, without needing a scientific calculator to hand. Secant is one of the six trigonometric functions, defined as the reciprocal of cosine, so sec(x) = 1 / cos(x), describing a fixed ratio in a right triangle or a length on the unit circle for a given angle. It comes up in geometry, trigonometry study, physics, engineering, surveying and navigation. You type the angle into the single input field and choose degrees or radians from the dropdown. The calculator converts your figure to radians behind the scenes, since that is what the underlying maths requires, then returns the secant value instantly, along with the same angle shown in both radians and degrees so you can check what you entered. Because secant is the reciprocal of cosine, it is undefined wherever cosine equals zero, at 90 and 270 degrees and every equivalent angle, and the calculator flags this rather than showing a false number. It is also periodic, repeating every 360 degrees (2 pi radians), so equivalent angles give the same result. Use it to check homework, verify hand calculations, or get a quick trig value mid-problem, and see the worked example and formula notes below for the maths spelled out step by step.

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