What is the characteristic of a scalene triangle?

A scalene triangle is defined by having no sides that are equal in length. This characteristic distinguishes it from other types of triangles. In an equilateral triangle, all three sides are of equal length, while in an isosceles triangle, at least two sides are equal. The absence of equal sides in a scalene triangle means that all three sides have different lengths, making it unique within the classification of triangles.

While scalene triangles can also have angles of various measures, the defining characteristic is the inequality of the sides, which directly relates to their overall shape and properties. The inclusion of a right angle, as mentioned in one of the other choices, is not necessary for a scalene triangle; it can be any type of triangle with unequal sides, including obtuse or acute angles. Thus, the focus on the lengths of the sides is what makes the identification of a scalene triangle straightforward and clear.