Triangle classification by side lengths distinguishes equilateral triangles, with three congruent sides; isosceles triangles, with exactly two congruent sides; and scalene triangles, with no congruent sides, using measured or labeled lengths rather than visual appearance. The understanding includes comparing side lengths consistently, recognizing that side-based classification is distinct from angle-based classification, and interpreting the resulting symmetry; it does not include more advanced algebraic or generalized classification beyond these standard cases.
To classify a triangle by its side lengths, compare the lengths of all three sides.
A triangle has side lengths
Step 1: Compare the side lengths.
The first two sides are both cm, so they are equal. The third side is cm, so it is different.
Step 2: Match the pattern.
There are exactly two equal sides.
Conclusion:
The triangle is isosceles.
Remember to use the labeled or measured side lengths, not how the triangle looks. This classification is based on sides, not on angles.
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