All three sides different lengths — so all three angles are different too. No equal pairs, no symmetry. The 'ordinary' triangle.
Drag the corners
isosceles · acute
angles sum ≈ 180°
Spotting a scalene triangle
- No two sides equal ⇒ no two angles equal.
- No lines of symmetry and no rotational symmetry — it can't map onto itself.
- It can still be right-angled, acute, or obtuse — 'scalene' only talks about side lengths, not angles.
- The biggest angle is always opposite the longest side; the smallest angle opposite the shortest side.
Your turn
A triangle has angles 50°, 60°, 70°. Is it scalene?
Most triangles you'd draw at random are scalene — equilateral and isosceles are the special, 'lucky' cases. Drag the corners above and try to *avoid* making any two sides equal.
Recap
- Scalene = all sides different ⇒ all angles different.
- No symmetry of any kind.
- Largest angle faces the longest side.