What type of triangle has at least two equal sides?

A triangle with at least two equal sides is classified as an isosceles triangle. This type of triangle is defined specifically by its side lengths, where two sides are of the same length, and the angles opposite those sides are also equal. This property is central to the definition of an isosceles triangle.

In contrast to other triangle types, a scalene triangle has all sides of different lengths and consequently all angles are also different. An equilateral triangle, while it does have equal sides, has all three sides equal, meeting a different criterion. A right triangle, on the other hand, is defined by having one angle that is exactly 90 degrees, which does not specify anything about the equality of the sides.

Thus, the correct choice highlights the key characteristic of the isosceles triangle: the presence of at least two equal sides.