Triangle Calculator
Calculate area, perimeter, and triangle type from three sides
Understanding Triangles
A triangle is a polygon with three sides and three angles. The sum of all interior angles in any triangle is always 180 degrees. This calculator uses the three side lengths to determine the triangle's properties using Heron's Formula.
A triangle with sides a, b, and c
Heron's Formula
Heron's formula calculates the area of a triangle when you know all three side lengths:
Triangle Types
Practical Examples
Calculate roof dimensions, support beam angles, and triangular structural elements
Determine property boundaries and plot areas using triangulation measurements
Create precise triangular shapes and calculate dimensions for logos and artwork
Learn and verify geometry problems, understand triangle properties and theorems
Triangle Inequality Theorem
For any triangle to be valid, the sum of any two sides must be greater than the third side:
3 + 4 = 7 > 5 ✓
4 + 5 = 9 > 3 ✓
3 + 5 = 8 > 4 ✓
1 + 2 = 3 < 5 ✗
Cannot form a triangle!
💡 Quick Tips
- ▸Right Triangles: If a² + b² = c², it's a right triangle (Pythagorean theorem)
- ▸Perimeter: Simply add all three sides together (a + b + c)
- ▸Units: Ensure all sides use the same unit of measurement
- ▸Equilateral Area: Can also use formula: Area = (√3/4) × side²