Trigonometry
The six circular functions, their inverses and identities, in degrees or radians, plus triangle solving. 13 tools, including Arccos Calculator, Arcsin Calculator, Arctan Calculator and Cosine calculator (cos). All free, with no account and nothing to install.
Arccos CalculatorFind the inverse cosine (arccos) of a value between −1 and 1, in degrees and radians.Arcsin CalculatorFind the inverse sine (arcsin) of a value between −1 and 1, in degrees and radians.Arctan CalculatorFind the inverse tangent (arctan) of any real value, in degrees and radians.Cosine calculator (cos)Enter an angle in degrees or radians and get its cosine, along with the secant (1/cos) and the same angle in the other unit. Exact for the common angles.Cosecant, Secant & Cotangent CalculatorGet csc, sec and cot for any angle at once, with undefined values flagged.Graphical degree sequence validatorCan a list of vertex degrees actually be realised by a simple graph? Enter the degrees and the Erdős–Gallai / Havel–Hakimi test decides whether the sequence is graphical — a real network with those connection counts exists — and explains the verdict.Sine CalculatorCompute the sine of any angle in degrees or radians, to your chosen precision.Tangent calculatorThe tangent of an angle, in degrees or radians, plus the sine and cosine it is built from — tan θ = sin θ / cos θ. It flags the undefined values at 90°, 270°… where the cosine is zero and the tangent runs off to infinity.Tangent Line to Circle CalculatorThe tangent lines from a point to a circle, with the tangent length and a live diagram.Trigonometric Equation SolverSolve sin, cos and tan equations on any interval by robust numerical root-finding — results as multiples of π, radians and degrees, with interval presets for [0,2π], [−π,π], [0,4π] and [0°,360°].Trigonometric Function GrapherPlot A·f(Bx − C) + D for sin, cos, tan, cot, sec and csc with the asymptotes drawn, plus amplitude, period, phase shift, midline, domain, range and key points.Trigonometric Identities CalculatorFrom one known function value and a quadrant, rebuild all six functions with the right signs, then check the Pythagorean, reciprocal, double-angle and half-angle identities.Interactive Unit Circle VisualizerDrag around the circle and watch all six functions move with the angle, in degrees and radians. Special angles give their exact values — √3/2, not 0.866 — the quadrant signs are named, and tan at 90° says undefined instead of printing a huge number.