All Transformations That Result in a Similar Image
All Transformations That Result in a Similar Image
When you hear that something is beingness transformed, you are non expecting it to wait anything like it did before. You may be expecting something new and different simply in mathematics, there is a term called similarity transformation. How tin can something be transformed and remain similar to what it used to be? This article volition focus on similarity transformations through dilations, and volition quickly get over rotations, reflections, and translations. Details and examples of rotations, reflections, and translations can exist found in Transformations.
Similarity and Transformations
When discussing similarity transformations, there are two terms to consider: similarity and transformation. Let’south start with a little introduction on what transformation and similarity mean.
A
transformation
in geometry means to modify the position or the shape of a geometric figure.
Similarity
is a belongings of geometric figures where the figures are of the same shape but different sizes.
We say two figures are similar when one tin be obtained from the other considering the ratio of their corresponding sides is equal. Like figures are of the same shape but different sizes. Consider the figure below.
The figure above shows two triangles of different sizes. The ratio of their corresponding sides is as well equal.
So, the triangles are similar. At present we know what transformation and similarity are individually, Allow’south see what similarity transformation is.
What is a Similarity Transformation?
When you accept 2 figures and 1 is being enlarged or reduced, we call that a similarity transformation.
A
similarity transformation
is when a figure is transformed into another through enlargement or reduction in size.
The figure in which the shape is being transformed into is chosen an
image,
while the original figure is chosen a
preprototype.
When dealing with similarity transformations, you will need a
scaling factor. To review the scale cistron, go to Volume, Area, Length and Dilations. From this article, recall if the scale cistron is
, and then the figure is being reduced. If
, and then the effigy is beingness enlarged.
Every point gets dilated from a stockstill point called the
eye of dilation. Consider the figure below.
In the above figure, point
is the center of dilation, fixed indicate used when dealing with calibration factors.
is existence dilated to
, significant it’s an enlargement because
is smaller than
. If yous have the distance of
to
you volition get a fraction that is equal to what you’ll get from taking the distance from
to
. This means that the property of similarity is still maintained despite the enlargement or reduction of the size of the figure. Mathematically, we write:
The prime number annotation (denoted every bit an apostrophe, ‘ ) is sometimes used to distinguish the labeling of the image and the preimage.
Let’southward look at an instance to show what we hateful.
Given
below with coordinates, a center of dilation
, and a scale factor of two.
Employ the dilation to the polygon and plot
.
Solution:
Stride 1: We volition offset by drawing the preimage
.
Stride two: From the question, we see that the scaling gene is 2. Notice that the calibration factor is greater than one. This means that it’s an enlargement. So, yous multiply each x and y coordinate of
by the scaling factor, 2. See the table below.
Step 3: We take multiplied by 2 to get the coordinates on the correct side of the table higher up. If you draw these new coordinates on the graph, you’ll become:
As you can see,
is the preepitome that has been transformed to the paradigm
^{
}.
Properties of similarity transformations
Hither are some properties of similarity transformations.

They occur when a effigy is enlarged or reduced to produce an image of the figure.

The corresponding sides of the preimage and its epitome should be of equal proportion.

The coordinates of the figure and its image should be of equal proportion.

There is a calibration factor
. If there is a figure
, the image of the figure will be
.
Finding similarity transformations – Examples
If the center of dilation is (0,0), nosotros tin multiply each 10 and y coordinate past the scale cistron, one thousand, to obtain the coordinates of the preimage. Mathematically,
PreParadigm Coordinate  Image Coordinate 
x,y 
The eye of dilation can be any signal on the cartesian plane, notwithstanding (0,0) is the most common in practice.
At present, let’s look at how to make up one’s mind if two figures are like or not with the postobit examples.
The figures on the graph beneath prove shapes with coordinates
Determine if they are similar or non.
Step 1: Make a diagram
As you tin see from the graph, the figures have been dilated meaning that some transformation has taken place.
Step two: The fastest way to check their similarities is to compare the coordinates of both figures. The first effigy is
and the 2nd is
. First, nosotros need to identify corresponding vertices. The rectangles are both in landscape orientation, and so we tin match the lesser left on one to the bottom left of the other and so on. You should get that P corresponds to West (both lesser left), S corresponds to Z (lesser right), Q to X (top left), and R to Y (peak right).
Next, we check
Step 3: Subbing in coordinates in the above equation, we get
Equally yous can see, the coordinates are not equal so similarity does non exist.
You lot’ll become the ratio of each coordinate to run across if they will accept the same scale cistron.
The outset gear up of coordinates to compare is
. The ratio will be
. They are equal.
The 2nd set is
(The ratio will exist
. Our result is non equal significant that the figures cannot be like. If we had got
instead of
, then we would have connected with the adjacent coordinate to see if we would get some other
as the scale gene. The calibration factor differs so, the figures are non like.
Another style to go almost this is to look at the graph itself. You should compare the respective sides of the figures and come across if they are of the same proportion.
From the figure,
is ii and
is 4. The proportion hither is
which is
.
is 4 and
is 7. The proportion here is
.
is very dissimilar from
.
Therefore, similarity does not exist.
Other Types of Similarity Transformations
There are other types of transformation in geometry like reflection, rotation, and translation. Equally mentioned at the offset of this article, examples involving these ones can be found in the article on Transformation.
Reflections
Reflection is when a figure is flipped to get a mirror image.
Rotations
Rotation is when the figure is turned most at a fixed point.
Translations
Translation is simply sliding the figure across the airplane.
These types of transformation mainly produce images that are coinciding to the original figures but sometimes they can be used when similarity cannot be adamant easily. Let’southward see how with the examples below.
Determine if the following figures are similar or not.
You can’t really tell if they are similar by just looking at information technology because they are placed in different positions. Let’s rotate and so translate the kickoff figure and see the issue.
Subsequently rotating and translating, the above figure was produced. Every bit y’all can meet, they are both in the same orientation and you can now make comparisons using respective parts.
The parts are in the aforementioned proportion. Therefore, they are like.
Similarity Transformations – Fundamental takeaways
 Similarity transformation is when a figure is transformed into some other through dilation. Dilation means to enlarge and reduce in size.
 We say two figures are similar when the ratios of their corresponding sides are equal.
 The figure into which the shape is beingness transformed is called an image, and the original shape is called the preprototype.
 If the center of dilation is 0, y’all just multiply the x and y coordinates of the preimage past the calibration factor to go the coordinates of the new epitome.
 The centre of dilation is a fixed betoken where every point gets dilated from.
 Other types of transformation in geometry include reflection, rotation, and translation.
All Transformations That Result in a Similar Image
Source: https://www.studysmarter.co.uk/explanations/math/geometry/similaritytransformations/