Classify triangles by side lengths

Triangle classification by side lengths means comparing the three side measures: an equilateral triangle has three equal sides, an isosceles triangle has exactly two equal sides, and a scalene triangle has three different side lengths. The learner interprets these categories from diagrams or numerical measures and understands that this classification concerns side equality, not angle size; triangle inequalities and combined side-and-angle classifications are outside this scope.

Detailed Explanation: Classify triangles by side lengths

To classify a triangle by its side lengths, compare the lengths of all three sides.

Equilateral: all 3 sides are equal.
Isosceles: exactly 2 sides are equal.
Scalene: all 3 sides are different.

Example

A triangle has side lengths $6\text{ cm}$ , $4\text{ cm}$ , and $6\text{ cm}$ . What type of triangle is it?

List the side lengths: $6$ , $4$ , and $6$ .
Compare them:
- The two sides measuring $6\text{ cm}$ are equal.
- The side measuring $4\text{ cm}$ is different.
Exactly two sides are equal.

Therefore, the triangle is isosceles.

Remember: This classification looks only at the side lengths, not at the angles.

Learn by doing: Classify triangles by side lengths

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Triangle Classification - Sides

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