Can I use this for non-right triangles?

Yes, this calculator works for any triangle shape - right, acute, or obtuse. It uses the Law of Cosines formula to find missing sides or angles.

Can I use this if I only know two sides and need the third side?

Yes, this calculator is designed exactly for that purpose. Enter two side lengths and the included angle, and it will compute the missing side length using the Law of Cosines formula.

What if I only know two sides and need the angle between them?

You can use the Law of Cosines in reverse - provide the three side lengths, and it will calculate the angles using the Law of Cosines formula.

TrigonometryTool Review

Law of Cosines Calculator

Provided byPi Day Calculatorspiday.org

Solves triangle problems using the law of cosines when two sides and an included angle are known.

One of 2 options for Law of Cosines Calculator

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About this tool

What Law of Cosines Calculator does

A concise reference tool for calculating side lengths and angles in any triangle using the Law of Cosines, suitable for students, educators, and professionals needing quick verification of side lengths or angles without manual calculation errors. It serves as a practical reference for geometry homework, construction planning, or any application requiring precise triangular calculations. The tool handles side-angle-side (SAS) scenarios where two sides and the included angle are known, allowing users to solve for the missing side or angle. It supports both degree and radian measures and handles edge cases where inputs may result in impossible triangles (returning appropriate error handling).

Step by step

How to use the Pi Day Calculators Law of Cosines Calculator

1
Enter known side lengths and angle measurements
2
Click 'Calculate' to compute unknown sides or angles
3
Review the step-by-step solution breakdown for verification

Is it right for you

Best for

Students, educators, and professionals needing quick, accurate triangle calculations without manual trigonometry errors

Limitations

Requires valid triangle inequality (sum of any two sides must exceed the third side)

Questions

Law of Cosines Calculator FAQ

Can I use this for non-right triangles?: Yes, this calculator works for any triangle shape - right, acute, or obtuse. It uses the Law of Cosines formula to find missing sides or angles.
Can I use this if I only know two sides and need the third side?: Yes, this calculator is designed exactly for that purpose. Enter two side lengths and the included angle, and it will compute the missing side length using the Law of Cosines formula.
What if I only know two sides and need the angle between them?: You can use the Law of Cosines in reverse - provide the three side lengths, and it will calculate the angles using the Law of Cosines formula.

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Omni Calculator
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