Triangle Calculator

Unlock the secrets of triangles with our powerful, free online calculator. Perfect for students, teachers, and professionals alike!

Triangle Analysis Results

Perimeter:
Area:
Angle A:
Angle B:
Angle C:
Triangle Classification:

Why Use Our Advanced Triangle Calculator?

  • Instant calculations for perimeter, area, angles, and triangle type
  • User-friendly interface suitable for students and professionals
  • Accurate results using proven mathematical formulas
  • Free to use with no registration required
  • Perfect for homework, geometry projects, and real-world applications

Understanding Triangle Types

Our calculator not only provides measurements but also classifies your triangle:

  • Equilateral: All sides and angles are equal
  • Isosceles: Two sides and two angles are equal
  • Scalene: No sides or angles are equal
  • Right: Contains a 90-degree angle
  • Acute: All angles are less than 90 degrees
  • Obtuse: One angle is greater than 90 degrees

How to Use the Triangle Calculator: A Step-by-Step Guide

Step 1: Enter Triangle Side Lengths

Input the lengths of all three sides of your triangle in the provided fields. Use consistent units (e.g., centimeters, inches).

Example: Side A = 3, Side B = 4, Side C = 5

Step 2: Click "Calculate Triangle Properties"

After entering the side lengths, click the "Calculate Triangle Properties" button to process your input.

Step 3: Interpret the Results

The calculator will display various properties of your triangle:

  • Perimeter: Sum of all sides
  • Area: Space inside the triangle
  • Angles: Interior angles A, B, and C
  • Triangle Classification: Type of triangle based on sides and angles

Math Examples

Example 1: Right Triangle (3-4-5)

Input: Side A = 3, Side B = 4, Side C = 5

Results:

  • Perimeter: 3 + 4 + 5 = 12
  • Area: √(s(s-a)(s-b)(s-c)) = √(6(6-3)(6-4)(6-5)) = 6
  • Angles: A ≈ 36.87°, B ≈ 53.13°, C = 90°
  • Classification: Scalene and Right

Example 2: Equilateral Triangle

Input: Side A = 5, Side B = 5, Side C = 5

Results:

  • Perimeter: 5 + 5 + 5 = 15
  • Area: (√3/4) * 5² ≈ 10.83
  • Angles: A = B = C = 60°
  • Classification: Equilateral and Acute

Example 3: Isosceles Triangle

Input: Side A = 5, Side B = 5, Side C = 8

Results:

  • Perimeter: 5 + 5 + 8 = 18
  • Area: √(s(s-a)(s-b)(s-c)) ≈ 12.5
  • Angles: A ≈ B ≈ 44.42°, C ≈ 91.17°
  • Classification: Isosceles and Obtuse

Tips for Using the Calculator

  • Ensure your side lengths can form a valid triangle (sum of any two sides must be greater than the third side).
  • Use consistent units for all side lengths.
  • For precise calculations, enter decimal values if necessary (e.g., 3.5 instead of 3 1/2).
  • Experiment with different side lengths to explore various triangle types and properties.