Enter the lengths of all three sides of the scalene triangle into the calculator to determine the area; this calculator can also evaluate any of the variables given the others are known.

Scalene Triangle Formula

The following formula is used to calculate the area of a scalene triangle:

A = sqrt(s * (s - a) * (s - b) * (s - c))


  • A is the area of the scalene triangle
  • s is the semi-perimeter of the triangle, calculated as (a + b + c) / 2
  • a, b, and c are the lengths of the triangle’s sides

To calculate the area of a scalene triangle, first calculate the semi-perimeter by adding the lengths of all three sides and dividing by 2. Then, subtract each side length from the semi-perimeter and multiply all the differences. Finally, take the square root of the result to obtain the area of the scalene triangle.

What is a Scalene Triangle?

A scalene triangle is a type of triangle that has all sides of different lengths. This means that none of the sides are equal in length, making it distinct from other types of triangles such as equilateral, where all sides are equal, and isosceles, where two sides are equal. In addition to having unequal sides, a scalene triangle also has unequal angles. The angles of a scalene triangle are all different, with none of them being 60 degrees, which is the case in an equilateral triangle.

How to Calculate Scalene Triangle?

The following steps outline how to calculate the area of a scalene triangle.

  1. First, measure the lengths of all three sides of the triangle (a, b, c).
  2. Next, calculate the semi-perimeter of the triangle using the formula: s = (a + b + c) / 2.
  3. Then, calculate the area of the triangle using Heron’s formula: A = √(s(s-a)(s-b)(s-c)).
  4. Finally, substitute the values of a, b, and c into the formula and calculate the area.
  5. After obtaining the result, check your answer with a calculator or by using a different method.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Side a = 5 units

Side b = 7 units

Side c = 9 units