Triangle Calculator

Calculate the area, perimeter, and other properties of any triangle instantly. Supports various formulas including Base & Height and Heron's Formula.

Perfect for geometry homework, construction projects, and design work. Get accurate results for equilateral, isosceles, and scalene triangles.

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Why Use Our Triangle Calculator?

Instant Results

Get the area or perimeter of any triangle in milliseconds. Simply enter the dimensions and get the answer immediately.

100% Accurate

Uses standard geometric formulas to ensure precision. Perfect for checking homework or for professional calculations in construction and design.

Educational

Learn about different types of triangles and the formulas used to calculate their properties. Great for students and teachers.

Understanding Triangles

A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. The sum of the internal angles of a triangle in a Euclidean space is always 180 degrees.

Formulas

  • Area (Base & Height):
    Area = ½ × base × height
  • Perimeter:
    Perimeter = a + b + c
  • Heron's Formula (Area from 3 sides):
    Area = √[s(s-a)(s-b)(s-c)]
    where s is the semi-perimeter: s = (a+b+c)/2

Types of Triangles

  • Equilateral: All three sides are equal in length.
  • Isosceles: Two sides are equal in length.
  • Scalene: All three sides have different lengths.
  • Right: Has one 90-degree angle.
  • Acute: All angles are less than 90 degrees.
  • Obtuse: Has one angle greater than 90 degrees.

Real-World Applications

🏗️ Architecture & Construction

Triangles are the strongest shape and are used in trusses, roofs, and bridges to provide stability and support weight.

🎨 Art & Design

Used in composition, perspective, and creating dynamic visual interest in graphic design and painting.

📡 Navigation & GPS

Triangulation is used by GPS systems to determine precise locations by measuring distances from multiple satellites.

🎮 Computer Graphics

3D models in video games and movies are built from thousands or millions of tiny triangles (polygons).

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Frequently Asked Questions

The most common formula for the area of a triangle is Area = (Base × Height) / 2. If you know the lengths of all three sides, you can use Heron's Formula. Our calculator supports both methods.
The perimeter of a triangle is the total distance around the outside of the triangle. It is calculated by adding the lengths of all three sides together: Perimeter = Side A + Side B + Side C.
Heron's Formula allows you to calculate the area of a triangle if you know the lengths of all three sides (a, b, c). First, find the semi-perimeter s = (a+b+c)/2. Then, Area = √(s(s-a)(s-b)(s-c)).
Based on side lengths, triangles are classified as: Equilateral (all 3 sides equal), Isosceles (2 sides equal), or Scalene (no sides equal).
Based on angles, triangles are classified as: Acute (all angles < 90°), Right (one angle = 90°), or Obtuse (one angle > 90°).
No. According to the Triangle Inequality Theorem, the sum of the lengths of any two sides must be greater than the length of the third side. If this condition is not met, the sides cannot form a closed triangle.