Definition
Scalene triangle
A scalene triangle is a triangle whose three side lengths are all different.
What it means
Measure the three sides. If no two side lengths match, the triangle is scalene. It can be tall, flat, narrow, or turned around; those appearances do not matter. The side-length pattern—different, different, different—is what decides.
Remember it
Three sides, three different lengths.
Example
Mina measures a triangle’s sides as 5 cm, 6 cm, and 8 cm. No two measurements match, so she classifies it as scalene.
Watch for
A triangle with two equal side lengths is not scalene; it belongs to the isosceles category.
Common mix-up
Scalene is about side lengths, not angle sizes. A scalene triangle may still have a right angle.
Exact meaning
A scalene triangle is a triangle with three pairwise unequal side lengths.