Trigonometry Calculator

Trigonometry Calculator gives all six functions of an angle -- sine, cosine, tangent and their reciprocals -- in degrees, radians or gradians, and works backwards from a ratio to an angle. The identity check at the bottom of the working prints sine squared plus cosine squared, which should always be one and is the quickest confirmation that the angle was interpreted the way you intended.

Tangent is reported as undefined where cosine is zero, rather than as a very large number. Tangent is sine divided by cosine, so at 90 and 270 degrees it has no value at all; floating point arithmetic will happily return something in the trillions, and treating that as an answer is how a calculation goes quietly wrong.

The inverse functions return one angle from their principal range, and the page says so. Because sine and cosine repeat, infinitely many angles share any given ratio: arcsin of 0.5 is 30 degrees, but 150 degrees has the same sine, and both matter when solving a triangle.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

• Shows sin, cos, tan, inverse result and angle in radians together, so you are not running it twice
• Prints the formula with your own figures substituted in
• Updates as you type, with no button to press and no page reload
• Copy the result in one click
• Free, no sign-up, and it runs entirely in your browser

The trigonometry calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Finding a side or angle in a right triangle
• Converting between degrees and radians
• Checking a trig value in homework
• Getting an angle back from a measured ratio