What is the Law of Sines?

Law of Sines: a/sin(A) = b/sin(B) = c/sin(C). It relates side lengths to the sines of opposite angles.

How do you calculate triangle area?

Area = 0.5 × a × b × sin(C) (using two sides and included angle). Also Heron's formula when all sides known.

Geometry & Trigonometry Suite

Triangle Solver + Trigonometry

Solve any triangle (SAS, SSS, ASA, AAS, SSA) – get missing sides, angles, area, perimeter. Also evaluate sin, cos, tan, arcsin, arccos, arctan with degree/radian support.

📐 Triangle Solver

Enter at least 3 values (including at least one side). The calculator will compute the rest.

🧮 Trigonometry Mode

Angle unit:

Enter value (angle or number)

Result

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Current mode: DEG (degrees)

💡 Loading geometry facts...

📖 Frequently Asked Questions

Q: How many values do I need to solve a triangle?

A: At least 3, including at least one side. For example, SSS (three sides), SAS (two sides + included angle), ASA (two angles + included side), AAS, or SSA (ambiguous case).

Q: What is the Law of Cosines?

A: c² = a² + b² – 2ab·cos(C). Used to solve triangles when you know two sides and the included angle (SAS) or all three sides (SSS).

Q: When to use degrees vs radians in trig mode?

A: Degrees are common in geometry (e.g., 30°, 45°). Radians are standard in calculus and physics (e.g., π/6). Our calculator supports both.

🧠 Trigonometry Formulas

sin(θ) = opposite/hypotenuse
cos(θ) = adjacent/hypotenuse
tan(θ) = sin(θ)/cos(θ) = opposite/adjacent
arcsin(x) returns angle whose sine is x
arccos(x) returns angle whose cosine is x
arctan(x) returns angle whose tangent is x

Tip: Our triangle solver uses these laws automatically. Try entering two sides and one angle!