Law of Cosines Calculator (c² = a² + b² - 2ab cos C)

Calculate third side length c of a triangle given two sides a, b and included angle C using the Law of Cosines.

How It Works & Processing Standards

Enter values above to calculate results automatically. Check each input field for guidance and units.

Example: a=3, b=4, angleCDegrees=90 → 5

Your input data is never sent to any server and is securely processed on your device.

Current Limits

  • Maximum input length: 100,000 characters

Law of Cosines Calculator (c² = a² + b² - 2ab cos C) is a 100% free, browser-based online utility. All calculations and file conversions run locally inside your browser (Local-First) without sending data to remote servers, keeping your documents and inputs strictly private.

How to Use Law of Cosines Calculator (c² = a² + b² - 2ab cos C)

  1. 1
    Enter Side aType first side length.
  2. 2
    Enter Side bType second side length.
  3. 3
    Enter Included Angle (°)Type angle between side a and b.

Common Use Cases

  • Calculating distance between two aircraft tracked from a common radar station
  • Structural truss member load angle engineering
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