What Is a Scalene Triangle Perimeter?
A scalene triangle is a triangle in which all three sides have different lengths (and consequently all three interior angles differ too). The perimeter is simply the total distance around the triangle — the sum of its three sides. This calculator adds sides a, b, and c to give you the perimeter instantly.
How to Use the Calculator
Enter the lengths of the three sides — a, b, and c — using any consistent unit (centimetres, metres, inches, feet, etc.). Click calculate and the tool returns the perimeter in the same unit. Because the formula is just addition, the calculator works for any triangle, but it is named for the scalene case where the three sides are unequal.
The Formula Explained
The perimeter formula is \(P = a + b + c\), where a, b, and c are the side lengths. There is no special variation for scalene triangles — every triangle's perimeter is the sum of its sides. For a valid triangle, the lengths must satisfy the triangle inequality: the sum of any two sides must exceed the third.
Worked Example
Suppose a triangle has sides a = 7 cm, b = 9 cm, and c = 12 cm. The perimeter is $$P = 7 + 9 + 12 = 28 \text{ cm}.$$ If instead the sides were 3, 4, and 5, the perimeter would be \(3 + 4 + 5 = 12\).
FAQ
Do the sides need to be different? For a triangle to be scalene, yes — all three sides differ. But the addition formula works for any triangle regardless.
What units should I use? Any unit you like, as long as all three sides use the same one. The perimeter comes out in that unit.
How is perimeter different from area? Perimeter measures the distance around the triangle (a length), while area measures the surface enclosed (a square unit). They require different formulas.
