1. The problem is to classify a triangle by its sides. 2. Triangles can be classified into three types based on their side lengths: - Equilateral: All three sides are equal. - Isosceles (but not equilateral): Exactly two sides are equal. - Scalene: All three sides are different. 3. To classify the given triangle, measure or know the lengths of its three sides. 4. Compare the side lengths: - If $a = b = c$, the triangle is equilateral. - If exactly two sides are equal, say $a = b \neq c$, it is isosceles but not equilateral. - If $a \neq b \neq c$, it is scalene. 5. Since the problem states options and no side lengths are given, the classification depends on the side lengths. Final answer: Use the side lengths to determine if the triangle is equilateral, isosceles (but not equilateral), or scalene.