Trigonometry calculator (sine, cosine, tangent)
Calculate the sine, cosine and tangent of an angle in degrees or radians.
How the calculation works
The three trig ratios relate an angle of a right triangle to its sides:
- sine = opposite ÷ hypotenuse
- cosine = adjacent ÷ hypotenuse
- tangent = opposite ÷ adjacent (= sine ÷ cosine)
Classic mnemonic: SOH-CAH-TOA.
Values worth memorizing
| Angle | sin | cos | tan |
|---|---|---|---|
| 30° | 0.5 | 0.866 | 0.577 |
| 45° | 0.707 | 0.707 | 1 |
| 60° | 0.866 | 0.5 | 1.732 |
What it's for
Finding a side or angle you can't measure directly: a building's height from its shadow, distances in navigation, force on a ramp.
Examples
- sin(30°) = 0.5; cos(60°) = 0.5; tan(45°) = 1.
- A 10 m shadow with the sun at 45°: height = 10 × tan(45°) = 10 m.
Frequently asked questions
Why is tan 90° undefined?
Because cos 90° is zero, and tangent is sine ÷ cosine (division by zero).
What is SOH-CAH-TOA?
A mnemonic: Sine = Opposite/Hypotenuse, Cosine = Adjacent/Hypotenuse, Tangent = Opposite/Adjacent.
Degrees or radians?
Here, enter the angle in degrees. Advanced math and programming default to radians.
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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources