geometry calculator

Law of Cosines Side Calculator

Law of Cosines Side Calculator for formula verification for 2D and 3D geometry work 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, included angle before calculating side c.
Rounding too early when the result still feeds another geometry or algebra step.

Example

7 units, 9 units, 60 deg gives Side C 8. 1854.

Formula

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

Use the two known sides and the included angle to solve for the third side.

The angle should be the one between the two known sides.

Next Step

FAQ

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

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