Suppose line k has equation x = 3. Compare the areas of ABCD and A'B'C'D' = ((1.2) ORK) (ABCD). Suppose ABCD is a rectangle with length and width w. Its area is given by the expression
change the value of the area. Therefore, the areas of ABCD and A'B'C'D'
a rectangle.
Rigid motions preserve lengths and widths, so they
be equal. Similar reasoning applies when ABCD is not