ΔABC undergoes a dilation by a scale factor. Using the coordinates of ΔABC and ΔA'B'C', prove that the triangles are similar by AA.

Given:
ΔABC undergoes a dilation by a scale factor and comes as ΔA'B'C'.
To show that both the triangles are similar.
Formula
If two triangles have three pairs of sides in the same ratio, then the triangles are similar.
[tex]Hypotenuse^2 = Base^2+Height^2[/tex]
Now,
In ΔABC,
AB = 18 unit
BC = 10 unit
So, [tex]AC^2 = AB^2+BC^2[/tex]
or, [tex]AC^2 = 18^2+10^2[/tex]
or, [tex]AC = \sqrt{424}[/tex]
Again,
In ΔA'B'C'
A'B' = 9 unit
B'C' = 5 unit
So, [tex]A'C' ^2 = A'B'^2+B'C'^2[/tex]
or, [tex]A'C'^2 = 9^2+5^2[/tex]
or, [tex]A'C' = \sqrt{106}[/tex]
Now,
[tex]\frac{AB}{A'B'} = \frac{18}{9} = 2[/tex]
[tex]\frac{BC}{B'C'} = \frac{10}{5} = 2[/tex]
[tex]\frac{AC}{A'C'} = \frac{\sqrt{424} }{\sqrt{106} } = 2[/tex]
Hence,
All the ratios are equal.
Therefore, we can conclude that,
ΔABC and ΔA'B'C' are similar.