How to calculate triangle area?

The area of a triangle is half the product of its base length and the corresponding height. Area = (base × height) / 2. Heron's formula can also be used to calculate the area of a triangle when all three sides are known.

How to calculate triangle perimeter?

The perimeter of a triangle is the sum of the lengths of its three sides. Perimeter = a + b + c, where a, b, c are the lengths of the triangle's sides.

What is Heron's formula?

Heron's formula is used to calculate the area of a triangle when all three sides are known. Formula: Area = √[s(s-a)(s-b)(s-c)], where s = (a+b+c)/2 is the semi-perimeter and a, b, c are the sides of the triangle.

What is a right triangle?

A right triangle is a triangle with one 90-degree angle (right angle). In right triangles, the Pythagorean theorem applies: a² + b² = c², where c is the hypotenuse and a and b are the other two sides.

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Triangle Calculator

Easily calculate area, perimeter and sides of triangles using different methods.

Calculation Method *

Three Sides (Calculate Area and Perimeter)

Base and Height (Calculate Area)

Right Triangle (Pythagorean Theorem)

Side a *

Side b *

Side c *

Leg a

Leg b

Hypotenuse c

Triangle Diagram

Triangle diagram automatically updates based on selected method and entered values.

Triangle type and measurements will be shown in calculation results.

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Calculation Results

Triangle properties have been calculated and are shown below

Triangle Type

Area and Perimeter

Area: -
Perimeter: -

Angles

Angle A: -
Angle B: -
Angle C: -

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How Does Triangle Calculator Work?

Different calculation methods and formulas

Three Sides Method

If you know the lengths of all three sides of a triangle, you can calculate its area using Heron's formula:

Area = √[s(s-a)(s-b)(s-c)]

Where s = (a+b+c)/2 (semi-perimeter)

Base and Height Method

If you know the base and height of a triangle, you can calculate its area using this formula:

Area = (base × height) / 2

Right Triangle Method

For right triangles, the Pythagorean theorem applies:

a² + b² = c²

Where c is the hypotenuse and a and b are the other two sides

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Frequently Asked Questions

Questions about triangle calculations

What is triangle inequality?

Triangle inequality states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. That is, if a, b, c are the sides of a triangle, then: a + b > c, a + c > b, and b + c > a must be true.

What is the sum of the angles in a triangle?

The sum of the angles in any triangle is always 180 degrees. Therefore, if A, B, C are the angles of a triangle, then: A + B + C = 180°.

What are the types of triangles?

Triangles can be classified into three types based on their sides:

Equilateral Triangle: A triangle with all three sides of equal length
Isosceles Triangle: A triangle with two sides of equal length
Scalene Triangle: A triangle with no sides of equal length

There are also three types of triangles based on their angles:

Acute Triangle: A triangle with all angles less than 90°
Right Triangle: A triangle with one angle equal to 90°
Obtuse Triangle: A triangle with one angle greater than 90°