Answer: Reflection across y axis.
Step-by-step explanation:
From the given picture, it can be seen that ∆A’B’C’ is the mirror image of ∆ABC.
Thus the transformation used here is reflection.
Since, the y coordinate of the corresponding vertices of both the triangles are exactly same . But the polarity of x coordinates changes.
It implies that all the corresponding points of both the triangles area equidistant from the y axis.
i.i. the line of reflection = y axis.
Hence, the used here is "Reflection across y axis".
