Triangle Theorems Calculator

  • Enter the lengths of Side A, Side B, and Side C of the triangle.
  • Select the unit for the side lengths from the dropdown menu.
  • Click "Calculate" to calculate various properties of the triangle.
  • View the results in the "Results" section below.
  • Results include perimeter, area, angles, triangle type, and more.
  • Check the "Calculation History" for previous calculations.
  • Click "Clear" to reset the input fields and results.
  • Click "Copy" to copy the results to the clipboard.

Calculation History


    The Triangle Theorems Calculator is a web-based tool designed to assist users in analyzing and understanding various properties of triangles. It provides an intuitive interface for inputting the lengths of the sides of a triangle and then calculates and displays information such as the type of triangle, its perimeter, area, and angles.

    Purpose and Concepts


    The primary purpose of the Triangle Theorems Calculator is to offer a quick and convenient way for users to perform geometric calculations related to triangles. It serves as an educational tool for students learning about geometry and provides a practical utility for professionals who need to analyze or design triangles in various applications.


    To comprehend the functionality of the Triangle Theorems Calculator, it’s essential to grasp several fundamental concepts related to triangles.

    1. Types of Triangles:
      • Equilateral Triangle: All three sides are of equal length.
      • Isosceles Triangle: Two sides are of equal length.
      • Scalene Triangle: No sides are of equal length.
    2. Perimeter:
      • The perimeter of a triangle is the sum of the lengths of its three sides.
      • Formula: Perimeter=Side A+Side B+Side C
    3. Area:
      • Heron’s Formula is used to calculate the area of a triangle when the lengths of its sides are known.
      • Formula: Area = √(s ⋅ (s – Side A) ⋅ (s – Side B) ⋅ (s – Side C)), where s is the semi-perimeter (s = Perimeter / 2).
    4. Angles:
      • The Law of Cosines is employed to calculate the angles of a triangle when the lengths of its sides are known.
      • Formula:
      • cos(A) = (B^2 + C^2 – A^2) / (2BC)
      • cos(B) = (C^2 + A^2 – B^2) / (2CA)
      • cos(C) = (A^2 + B^2 – C^2) / (2AB)

    Benefits of the Triangle Theorems Calculator

    Educational Aid

    The calculator serves as an educational aid by providing a hands-on approach to learning geometric concepts. Students can input values, observe results, and gain a deeper understanding of the relationships between triangle sides, angles, and types.

    Time-Saving Tool

    Professionals working in fields such as architecture, engineering, or physics can use the calculator to quickly assess triangle properties without manual calculations. This can save time and improve accuracy in design and analysis processes.

    Interactive Learning

    The interactive nature of the tool engages users in the learning process. By allowing them to experiment with different side lengths, users can observe how changes impact the type of triangle and associated properties.

    Interesting Facts about Triangles

    Pythagorean Theorem

    One of the most famous theorems related to triangles is the Pythagorean Theorem, which states that in a right-angled triangle, the square of the length of the hypotenuse (c) is equal to the sum of the squares of the lengths of the other two sides (a and b): c^2 = a^2 + b^2.

    Triangle Inequality Theorem

    The Triangle Inequality Theorem asserts that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. This concept is crucial for determining whether a set of side lengths forms a valid triangle.

    Golden Triangle

    The Golden Triangle, also known as the sublime triangle, is an isosceles triangle in which the duplicated side is in the golden ratio to the base side. The golden ratio is approximately 1.618 and has fascinating mathematical and aesthetic properties.


    Understanding the properties and theorems related to triangles is fundamental in mathematics and geometry. For an in-depth exploration, the following scholarly references are recommended:

    1. “Geometry” by Euclid (circa 300 BCE):
      • Euclid’s “Elements” is a comprehensive compilation of mathematical knowledge, including extensive coverage of geometry and theorems related to triangles.
    2. “Elements of Trigonometry and Trigonometrical Analysis” by Elias Loomis (1850):
      • Loomis’ work is a classic in the field of trigonometry, providing detailed insights into the relationships between angles and sides in triangles.
    3. “Geometry: A Comprehensive Course” by Dan Pedoe (1988):
      • Pedoe’s book covers a wide range of geometric topics, offering clear explanations and examples related to triangles and their properties.
    4. “Introduction to Algorithms” by Thomas H. Cormen et al. (2009):
      • While not exclusively focused on geometry, this influential textbook discusses algorithms related to geometric problems, including those involving triangles.


    The Triangle Theorems Calculator serves as a valuable tool for both learners and professionals, offering a practical and interactive way to explore the properties of triangles. Understanding the underlying concepts, formulas, and theorems enhances mathematical knowledge and facilitates efficient problem-solving in various disciplines. Whether used for educational purposes or professional applications, the calculator contributes to a deeper appreciation of the intriguing world of triangles and their mathematical significance.

    Last Updated : 27 February, 2024

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    24 thoughts on “Triangle Theorems Calculator”

    1. The interactive learning experience provided by the Triangle Theorems Calculator is a valuable asset for students gaining insights into triangle properties. It also serves as a practical utility for professionals needing to analyze and design triangles.

    2. The Triangle Theorems Calculator is an excellent educational aid that effectively engages users in learning geometric concepts. It is a much-needed time-saving tool for professionals in various fields, providing an efficient approach to triangle analysis.

    3. I completely agree. The calculator’s benefits for educational and professional purposes are undeniable, and its user-friendly interface makes it a valuable learning tool.

    4. The Triangle Theorems Calculator provides a valuable means of interaction with and exploration of triangle properties. It’s an interesting educational tool for students and a convenient utility for professionals.

    5. Absolutely, Hill. The ability to experiment with different side lengths and observe the resulting changes enhances understanding and facilitates practical applications of triangle properties.

    6. The Triangle Theorems Calculator offers a beneficial approach to understanding triangle properties and their practical applications. Its interactive nature makes it an engaging educational tool for learners across various levels.

    7. The Triangle Theorems Calculator provides an efficient and engaging approach to learning about triangles and their properties. Its application in various disciplines demonstrates the practical significance of geometric knowledge.

    8. Absolutely, Zoe. It encourages users to experiment with different side lengths and observe the corresponding changes, which is incredibly beneficial for learning.

    9. The Triangle Theorems Calculator is an innovative tool that effectively combines theoretical geometric knowledge with practical utility. It’s beneficial for educational purposes as well as professional applications.

    10. Definitely, Roberts John. The calculator effectively combines theoretical and practical aspects of triangles, promoting a comprehensive understanding of their properties and significance.

    11. Definitely! It’s a great way to visualize and understand triangle properties without the need for extensive manual calculations.

    12. Absolutely, Yclarke. Its benefits for both educational and practical purposes contribute to a deeper appreciation of the mathematical significance of triangles.

    13. The Triangle Theorems Calculator is an intriguing and practical tool for learners and professionals alike. Its representation of fundamental concepts and interesting facts about triangles promotes a comprehensive understanding of geometric properties.

    14. I completely agree. The calculator is a valuable learning resource that contributes to a deeper appreciation of geometric concepts and their real-world applications.

    15. The Triangle Theorems Calculator offers a practical approach to exploring geometric concepts and understanding triangle properties. It’s beneficial for professionals in architecture, engineering, and physics, as well as for students learning about geometry.

    16. Absolutely, and the fact that it provides hands-on learning experience makes it a great way to deepen understanding of triangle properties.

    17. Definitely, Mia73. The calculator’s ability to combine theoretical knowledge with practical application makes it a valuable asset for exploring the world of triangles.

    18. Indeed, Xadams. Its time-saving capabilities and engaging interface make it a highly valuable resource for both learners and professionals.

    19. This calculator presents an innovative and interactive way to explore the intriguing world of triangles and their mathematical significance. It’s a valuable educational aid and problem-solving tool.

    20. The interactive learning experience offered by the calculator is a key factor in enhancing understanding of triangles and their properties.

    21. The Triangle Theorems Calculator serves as a valuable educational and practical tool for understanding and analyzing triangles. Its inclusion of interesting facts about triangles further enriches the learning experience.

    22. I completely agree. The calculator’s ability to engage users in interactive learning and provide practical insights makes it an invaluable resource for students and professionals alike.

    23. Absolutely, Martin King. The incorporation of fascinating facts enhances the overall learning experience and contributes to a deeper appreciation of triangle properties and significance.

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