geometry calculator

Law of Cosines Angle Calculator

Law of Cosines Angle Calculator for coordinate geometry, angles, and diagram-based problems when you want a fixed formula answer without improvising the math by hand.

Important Use Notice

Informational calculator only. Verify important outputs independently before legal, tax, medical, engineering, safety-critical, contractual, employment, or compliance use.

Estimate

Enter job values, review the estimate, then use the decision hints before ordering or quoting.

Estimate Results

Enter values to see the result.

Check

Mixing units, scales, or coordinate conventions across side a, side b, opposite side before calculating angle c.
Rounding too early when the result still feeds another geometry or algebra step.

Example

7 units, 8 units, 9 units gives Angle C 73. 3985.

Formula

cos(C) = (a^2 + b^2 - c^2) / 2ab

Solve for the cosine first, then take the inverse cosine to recover the angle.

This works when all three side lengths are known.

Next Step

FAQ

When should I keep more decimals for law of cosines angle calculator?

Keep more precision when the output will feed another formula, drawing, coordinate step, or comparison rather than being rounded once and left alone.