Triangle Calculator - Calculate Triangle Area and Properties

Calculate triangle properties using various methods depending on known values: base and height, three sides (SSS), or two sides and included angle (SAS).

1. 1

   Step 1

   Enter the lengths of all three sides (a, b, c)

2. 2

   Step 2

   The calculator verifies the triangle is valid (sum of any two sides greater than the third)

3. 3

   Step 3

   The semi-perimeter (s) = (a+b+c)/2 is calculated

4. 4

   Step 4

   Heron's formula is applied to calculate the area

5. 5

   Step 5

   Angles are calculated using the law of cosines

• 1

  A 3-4-5 triangle is a commonly used right triangle

• 2

  The sum of angles in any triangle is always 180 degrees

• 3

  An equilateral triangle has all equal sides and 60-degree angles

• 4

  The law of cosines is a generalization of the Pythagorean theorem

• 5

  The circumscribed circle passes through all three vertices, the inscribed circle touches all three sides

• Confusing height with side length

• Using slant height instead of perpendicular height

• Forgetting to divide by 2 in the area formula

• Not checking if given sides can form a valid triangle