In each diagram, ∆ABC has been transformed to yield ∆A'B'C'. Which transformation could NOT be achieved by rotation alone?





Answer: The ∆ABC has been transformed to yield ∆A'B'C'. The fourth diagram shows that the transformation could NOT be achieved by rotation alone.
Explanation:
In first figure ∆ABC has been transformed to yield ∆A'B'C' by rotation of 180 degree either clockwise or counterclockwise along the midpoint of AB.
The second and third figure are same. In both figures ∆ABC has been transformed to yield ∆A'B'C' by rotation of 180 degree either clockwise or counterclockwise along the origin.
In fourth figure ∆ABC has been transformed to yield ∆A'B'C' by rotation of 180 degree either clockwise or counterclockwise along the origin.
But only in fourth figure ∆ABC has been transformed to yield ∆A'B'C' by reflection along the x-axis.
Therefore, the correct option is 4th diagram.