Law of Cosines Calculator - Find c²=a²+b²-2abcosC

Law of Cosines Calculator

Solve triangles using c² = a² + b² - 2ab·cos(C)

Sides:
Angles (degrees):
Angle unit:
Try Examples:

About the Law of Cosines

Law of Cosines: For any triangle with sides a, b, c and opposite angles A, B, C:

c² = a² + b² - 2ab·cos(C)

b² = a² + c² - 2ac·cos(B)

a² = b² + c² - 2bc·cos(A)

When to Use:
  • SAS: Two sides and included angle
  • SSS: All three sides known
  • When Law of Sines doesn't apply
Special Cases:
  • When C = 90°: c² = a² + b² (Pythagorean theorem)
  • When C > 90°: cos(C) < 0
  • When C < 90°: cos(C) > 0

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Law of Cosines Calculator - Find c²=a²+b²-2abcosC

📅 Published:
Law of Cosines Calculator solving SSS or SAS triangles with c² = a² + b² − 2abcosC and a labeled triangle diagram.

A Law of Cosines Calculator saved my business when I needed to calculate precise measurements for a custom gaming setup at one of my early Kupi Key gaming events. We were designing a triangular stage layout with specific dimensions, but one crucial measurement was missing. The event was scheduled for the next day, contractors were waiting, and mental math wasn't giving me the confidence I needed for such an expensive setup.

This calculation tool isn't just for academic exercises. It's a practical solution for anyone dealing with real-world triangular measurements in business, construction, or design projects. For complementary trigonometric functions, our cos calculator provides essential cosine computations. The mathematical precision this utility provides eliminates costly measurement errors and gives you confidence in your planning decisions.

How Do You Use the Law of Cosines Calculator?

Law of Cosines Calculator: Solve SAS and SSS

Using our law of cosines calculator is simple when you understand the triangle scenarios it handles. You need either three sides (SSS case) or two sides and the included angle (SAS case). Input your known measurements into the appropriate fields. Our mathematical tool automatically applies the formula c² = a² + b² - 2ab·cos(C) to find missing values. For scenarios involving angles and opposite sides, our law of sines calculator provides complementary triangle solving capabilities. The system shows step-by-step calculations, making it perfect for both quick results and educational understanding.

The Law of Cosines Calculator finds missing sides and angles for SAS and SSS cases and validates your inputs against triangle‑inequality constraints.

What are the Key Features of Our Triangle Calculator?

Our digital calculator offers advanced features for precise triangular calculations. We've built this mathematical utility to handle complex scenarios while maintaining user-friendly operation.

  • Smart Case Detection: Automatically recognizes SAS and SSS triangle configurations for optimal calculation methods.
  • Complete Solution Process: Displays every calculation step from initial formula application to final triangle validation.
  • Triangle Inequality Validation: Automatically checks that your measurements form a valid triangle before processing calculations.
  • Business-Grade Precision: Provides results accurate to four decimal places for professional construction and design applications.

What are the Main Applications of This Calculation Tool?

This versatile mathematical tool serves professionals across multiple industries. It provides reliable results that remove guesswork from critical measurements.

🏢How Can This Tool Boost Your Business Efficiency?

Perfect for entrepreneurs who need precise measurements for physical setups, retail displays, or event staging. When planning a triangular booth layout with sides of 8 feet and 12 feet meeting at a 60° angle, this law of cosines calculator instantly determines the third side is 10.58 feet, allowing accurate material ordering and cost estimation.

🎓Is This Mathematical Tool Essential for Students?

Absolutely essential for geometry and trigonometry students tackling advanced triangle problems. The detailed solution steps help students understand the logical progression from given information to final answers. This builds mathematical confidence and problem-solving abilities. For comprehensive trigonometry resources, students can access University of Utah's Online Mathematics courses which provide extensive triangle calculation practice.

💼Why is This Web-Based Tool Vital for Professionals?

This browser-based tool serves architects, contractors, and engineers who require immediate triangular calculations on-site. Unlike complex software, it works instantly on any device. My experience managing multiple business ventures taught me that quick, accurate calculations often determine project success. Whether you're sizing roof trusses or planning landscape triangulations, reliability matters more than complexity.

Can This Digital Calculator Handle Advanced Triangle Problems?

A basic law of cosines calculator works well for standard scenarios. Advanced applications require sophisticated validation systems.

Our computational tool automatically detects impossible triangle configurations, preventing wasted time on invalid measurements. It recognizes when triangle inequality is violated (where the sum of two sides equals or is less than the third side) and provides clear error messages. This level of intelligence separates professional tools from simple educational calculators.

For complex architectural projects involving multiple triangular elements or 3D spatial calculations, you might need additional geometric tools alongside this fundamental triangle relationship calculator. Our comprehensive triangle area calculator complements this tool perfectly for complete geometric analysis. However, the law of cosines forms the foundation for most advanced triangular computations.

About the Author

Jurica Šinko - Founder & CEO

Jurica Šinko

Founder & CEO, AI Math Calculator

Varaždin, Croatia
Mathematical Software Expert

Croatian entrepreneur and youngest company director at age 18. Combines mathematical precision with business innovation to create accessible educational tools for millions of users worldwide.

Why is This the Best Triangle Calculation Choice?

To sum up, our Law of Cosines Calculator - Find c²=a²+b²-2abcosC is a comprehensive, reliable, and accessible solution for your triangular calculation needs. It combines mathematical precision with user-friendly operation, making complex trigonometric relationships manageable for students and professionals alike. The automatic validation and step-by-step explanations ensure both accuracy and educational value. Bookmark this page and discover the power of professional mathematical computation made simple.

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