When comparing two triangles using transformations, which property remains constant?

When comparing two triangles using transformations, the properties that remain constant are both shape and size. Transformations such as translations, rotations, and reflections do not alter the fundamental characteristics of the triangles; they remain congruent, meaning that their corresponding sides and angles are equal.

The shape is preserved because transformations do not change the angles or the relationships between the sides of the triangles. Similarly, the size is preserved as congruent triangles maintain the lengths of their corresponding sides. Therefore, when triangles are compared through such transformations, both shape and size remain constant, highlighting the congruence between the two figures.

The options regarding area and size alone are not comprehensive, as congruence involves both aspects. While it is true that congruent triangles also have equal areas, this property is inherently tied to their shape and size being identical, rather than a standalone constant when considering basic transformations like the ones mentioned.