Reflection of a two dimensional figure in a line

Author:
Mathguru
On the screen, we see a triangle ABC in red color. Observe how the shape of the triangle A’B’C’ (green color) changes as we move the points A, B and C. Triangle A’B’C’ is the reflection of the triangle ABC in x-axis
Questions to think about; 1. What is the relation between the co-ordinates of A and A’, B and B’ and C and C’? 2. Find where are the midpoints of AA’, BB’ and CC’.