http://www.ck12.org Chapter 12. Rigid Transformations
A( 8 , 8 )→A′′(− 8 , 0 )
B( 2 , 4 )→B′′(− 2 ,− 4 )
C( 10 , 2 )→C′′(− 10 ,− 6 )
Example B
Write a single rule for 4 ABCto 4 A′′B′′C′′from Example A.
Looking at the coordinates ofAtoA′′, thex−value is the opposite sign and they−value isy−8. Therefore the rule
would be(x,y)→(−x,y− 8 ).
Notice that this follows the rules we have learned in previous sections about a reflection over they−axis and
translations.
Example C
Reflect 4 ABCovery=3 andy=−5.
Unlike a glide reflection, order matters. Therefore, you would reflect overy=3 first, followed by a reflection of this
image (red triangle) overy=−5. Your answer would be the green triangle in the graph below.