The transformation here is rotation.
From the given picture it can be seen that the size of both triangles are equal. Since both triangles are congruent by Side side side Congruence rule.
It means there is transformation only.
There are three common transformations exist:
Reflection:- A reflection is a transformation that generally flips a shape over a line of reflection( acts as mirror) such that it produces the mirror image of the Object.
Rotation:- A rotation rotate a figure about a fixed point . It usually changes the orientation of the figure or the vertex of the triangles.
Translation:- A translation is a transformation of a figure that moves each point of the figure a exact distance in a particular direction. Here orientation of figure remains unchanged .
Here clearly we can see that the figure got a total rotation of 180 degrees in anti clock wise direction.
Hence the transformation here is rotation.
For more details on rotation symmetry follow the link:
https://brainly.com/question/1597409