Answer:
The angle measures remain same from the preimage to the image.
The side lengths measures remain same for the preimage to the image.
This is an example of rigid transformation.
Explanation:
Consider ΔABC and ΔA'B'C'
AC=A'C'=2 units (as drawn)
BC=B'C'=2 units (as drawn in graph)
∠ACB=∠A'C'B'=90°
Therefore, by Side Angle Side(SAS) axiom of congruency ΔABC and ΔA'B'C' are congruent.
In congruent triangles, side lengths and angle values are equal to each other.
∴
The angle measures remain same from the preimage to the image.
The side lengths measures remain same for the preimage to the image.
If the side lengths remain the same in a transformation it is known as rigid transformation, therefore it is also a rigid transformation due to the reflection by line l.