Transformations: Translations and Reflections

Translations on a Coordinate Axis

In geometry, we often use a coordinate axis to show specific translations.  By using the coordinate axis, we can specify how many units to translate an object, to the left, right, up or down.

To see how this works, let’s look at just one point and the changes in coordinates when translations are performed.

Start with the point (3, 4).  Translate it 2 units to the right.  What is the new point?

the point (3, 4) translated 2 units to the right
(3, 4) Translated 2 Units to the Right

 

As you can see, the new point is (5, 4).  Notice that the y-coordinate did not change, but the x-coordinate increased by 2.

Now take the same point (3, 4) and translate it 2 units to the left.  What is the new point?

the point (3, 4) translated 2 units to the right the point (3, 4) translated 2 units to the right
(3, 4) Translated 2 Units to the Left

 

As you can see, the new point is (1, 4).  Notice that the y-coordinate did not change, but the x-coordinate decreased by 2.

Now let’s look at translating the point (3, 4) up and down.  Translate the point up 2 units. Then, from the original position of the point, translate it down 2 units.  What are the new points?

the point (3, 4) translated 2 units up and 2 units down
(3, 4) Translated 2 Units Up and 2 Units Down

 

As you can see, when the point is translated up 2 units the new point is (3, 6).  Notice that the x-coordinate did not change, but the y-coordinate increased by 2.

When the point is translated down 2 units the new point is (3, 2).  Notice that the x-coordinate did not change, but the y-coordinate decreased by 2.

Summary:


Translation:

Change in x-coordinate

Change in y-coordinate

Right

Increases

No Change

Left

Decreases

No Change

Up

No Change

Increases

Down

No Change

Decreases


Keep in mind that a point might be translated left/right AND up/down.  We will look at some examples of this in the next couple of pages.