Skip to main content
RK
Rojony Khatun
Last updated: Jun 15, 2026

Triangle Law Of Cosines

Calculate unknown sides or angles of any triangle using the Law of Cosines. Perfect for students, engineers, and designers working with triangles online.

Advertisement
Advertisement
Triangle Law Of Cosines
Advertisement

Triangle Law Of Cosines

Calculate unknown sides or angles of any triangle using the Law of Cosines. Perfect for students, engineers, and designers working with triangles online.

Advertisement

triangle formulas calculator

A Triangle Law of Cosine Calculator enables one to easily find unknown sides or angles of a triangle with the help of the Law of Cosine. It uses two sides on one side and the angle contained on the other side, and calculates all the other measurements on the triangle immediately, so it is mathematically useful in education, engineering, and design.

triangle measurement calculator

The Triangle Law of Cosines Calculator is an online tool that helps compute unknown sides or angles of any triangle using the Law of Cosines formula

\[ c^{2} = a^{2} + b^{2} - 2ab \times cos(C) \]

The calculator automatically gives the side or angle that was not known by typing the known sides and angles. The tool would be best when the student, engineer, architect, and designer require the precise triangle measurements during math calculations, construction work, or even in designing. It minimizes errors in the calculations made manually and saves time. The interface is easy, reacts quickly, and does not need any installation, which provides immediate and precise results for any triangle setup.

Sponsored

Work, Installation, Input to Output

Work:

  • Accepts two sides and the included angle or three sides.
  • Uses Law of Cosines: \( \)
  • Computes missing side or angle in degrees.
  • Displays results instantly.

Installation: No installation required; works in any modern web browser.

Input:

  • Two sides + included angle OR three sides

Output:

  • Missing side
  • Missing angle(s)

Testing and Final Adjustments

Experiment with triangles of every kind of angle (acute, right, obtuse). Meanwhile, by hand calculating values through the formula of cosine. Treat bad data, such as negative sides or angles over 180. Check that there are the results which are rounded correctly and the angles are in the acceptable ranges. Mobile and desktop response testing. Output immediate changes as inputs are altered. Hindrance Reporting. Present the results in a clear and unified manner. Finally, optionally, a little triangle diagram that will update itself with the input values.

Advertisement

Frequently Asked Questions - Triangle Law Of Cosines:

A tool to calculate unknown sides or angles of a triangle using the Law of Cosines.
Enter two sides and the included angle or all three sides to compute missing measurements.
c² = a² + b² - 2ab * cos(C) for sides or cos(C) = (a² + b² - c²)/(2ab) for angles.
Yes, this calculator is completely free online.
Yes, it works on all devices and is fully responsive.
Yes, calculations are displayed instantly upon input.
Students, engineers, architects, and designers.
Yes, it supports decimals and precise inputs.
Yes, it works for all triangle types as long as inputs are valid.
It saves time, ensures accurate triangle calculations, and aids math, engineering, and design tasks.
Advertisement
Advertisement
Advertisement