Sine, cosine, tangent and their inverses — in degrees or radians, plus triangle solving.
Result
TrigonometryHow to use this tool
Use Trig function for sin, cos, tan, cosec, sec or cot of an angle; Inverse function to find the angle from a ratio (for example arcsin 0.5); or Right triangle to solve a whole right triangle from one side and one angle.
Angles can be entered in degrees or radians — switch the unit and the trigonometry calculator converts for you. For inverse functions, remember arcsin and arccos only accept values from −1 to 1.
The result panel shows sin, cos and tan together, so you can check your working at a glance, plus the angle in both degrees and radians.
In Right triangle mode, tell the calculator which side you know — hypotenuse, opposite or adjacent — and one acute angle, and it returns every side, both acute angles, area and perimeter.
Formula & worked example
Worked example: sin 30° = 0.5, cos 60° = 0.5 and tan 45° = 1. In the other direction, arcsin(0.5) = 30° and arctan(1) = 45°. Right-triangle example: a hypotenuse of 5 with an acute angle of 36.87° gives an opposite side of 3.00, an adjacent side of 4.00, the other angle 53.13°, area 6 and perimeter 12 — the familiar 3-4-5 triangle.
Limitations — read this before you rely on it
tan and sec are undefined at 90°, 270° and so on (where cos = 0), and cot and cosec are undefined at 0° and 180° (where sin = 0) — the calculator says so plainly instead of returning a huge misleading number. Inverse sine and cosine return only the principal value (arcsin between −90° and 90°, arccos between 0° and 180°); other angles with the same ratio exist and are found by adding 360° or using symmetry. Results are rounded for display; the underlying values keep full precision.
Frequently asked questions
A trigonometry calculator evaluates the trigonometric functions — sin, cos, tan and their reciprocals — for any angle, and the inverse functions that recover the angle from a ratio. This one also solves a right triangle from one side and one angle.
Multiply degrees by π ÷ 180. So 180° = π radians (≈ 3.1416), 90° = π ÷ 2 and 30° = π ÷ 6. This calculator accepts either unit and shows both.
Because tan θ = sin θ ÷ cos θ, and cos 90° = 0. Dividing by zero is undefined, so tan shoots off to infinity on either side of 90° instead of settling on a value.
Sin takes an angle and returns a ratio (sin 30° = 0.5); arcsin does the reverse, taking a ratio and returning the angle (arcsin 0.5 = 30°). They undo each other within their principal ranges.
Use SOH CAH TOA: if you know the hypotenuse and an angle, opposite = hypotenuse × sin(angle) and adjacent = hypotenuse × cos(angle). The other acute angle is 90° minus the known one. The Right triangle mode here does all of it for you.