Which of the following best describes an isosceles triangle?

• A. All sides are unequal
• B. It has 3 equal sides
• C. It has 2 equal sides
• D. It has one right angle

Answer: (C)

An isosceles triangle is defined as a triangle that has two of its sides equal in length. This property leads to two angles, known as the base angles, being equal as well. The defining characteristic of having two equal sides distinguishes isosceles triangles from other types, such as scalene triangles, which have all sides of different lengths, and equilateral triangles, where all three sides are of equal length. Additionally, while some isosceles triangles can have a right angle, this is not necessary for the definition; thus, there can be isosceles triangles that are obtuse or acute. Therefore, the option stating it has two equal sides accurately describes the isosceles triangle and aligns with the fundamental geometric properties of this shape.