501 Geometry Questions

How are Transformations Named?

All transformations use the same method for referring to the original image
and naming the transformed image. The original image is called the preim-
age and the new figure is called the image. When a point undergoes a trans-
formation, it keeps the same name, but is followed by a prime mark ('). For
example, after point Q is transformed, it becomes Q', which is said, “Q
prime.” Look at the transformation of polygon ABCD in the following fig-
ure. Notice that the image it creates is named A'B'C'D'.

Transformation

y

A

ABCD Is the Preimage. A'B'C'D' Is the Image.

B

C

D

A'

B'

C'

D'

501 Geometry Questions