484,529 views
22 votes
22 votes
Create a transformation that is not a similarity transformation. Explain why your transformation wouldn’t be similar

User Evorage
by
2.7k points

1 Answer

18 votes
18 votes

Two figures are similar if they have the same shape. This means that two similar figures have the same internal angles although their size and orientation may be different. A similarity transformation maps a figure onto another figure that is similar. Here we must find a non-similarity transformation i.e. a transformation that maps a figure onto a non-similar figure. In order to see this let's build any figure in the coordinate plane, for example, a triangle:

Now let's define a transformation, i.e. an operation over the coordinates of the points in the grid. Let's use (x,y) for any generic point and the transformation is:


(x,y)\rightarrow(x,(y)/(2))

So this tranformation takes a point and divides its y-coordinate by 2. Let's apply it to the three points that define the triangle in the figure:


\begin{gathered} A=(0,0)\rightarrow A^(\prime)=(0,(0)/(2))=(0,0) \\ B=(3,0)\rightarrow B^(\prime)=(3,(0)/(2))=(3,0) \\ C=(3,3)\rightarrow C^(\prime)=(3,(3)/(2))=(3,1.5) \end{gathered}

Then we graph the new transformed triangle A'B'C':

As you can see two of the angles of A'B'C' don't match with the angles of ABC. This means that ABC and A'B'C' are not similar. Therefore this transformation is not a similarity transformation.

In summary, the answer is that the transformation (x,y)⇒(x,y/2) is not a similarity transformation because it doesn't keep the shape of the figures it transforms.

Create a transformation that is not a similarity transformation. Explain why your-example-1
Create a transformation that is not a similarity transformation. Explain why your-example-2
User Charisma
by
2.4k points