Geometry

Question Analysis:
This question tests the definition of an isosceles triangle.

Key Concept Explanation:
An isosceles triangle has at least two sides congruent (equal in length).
The angles opposite these sides (base angles) are also congruent.

Step-by-Step Solution:
Recall the definition: An isosceles triangle has ≥2 equal sides.
Option A matches this definition.
Option B describes an equilateral triangle (a special case of isosceles).
Option C refers to a right triangle, not necessarily isosceles.
Option D is false because isosceles triangles always have ≥2 equal angles.

Common Mistakes:
Confusing isosceles ...