http://www.ck12.org Chapter 12. Rigid Transformations
Common Reflections
- Reflection over they−axis:If(x,y)is reflected over they−axis, then the image is(−x,y).
- Reflection over thex−axis:If(x,y)is reflected over thex−axis, then the image is(x,−y).
- Reflection overx=a: If(x,y)is reflected over the vertical linex=a, then the image is( 2 a−x,y).
- Reflection overy=b: If(x,y)is reflected over the horizontal liney=b, then the image is(x, 2 b−y).
- Reflection overy=x:If(x,y)is reflected over the liney=x, then the image is(y,x).
- Reflection overy=−x:If(x,y)is reflected over the liney=−x, then the image is(−y,−x).
Example A
Reflect the letter "F" over thex−axis.
To reflect the letterFover thex−axis, now thex−coordinates will remain the same and they−coordinates will be
the same distance away from thex−axis on the other side.
Example B
Reflect 4 ABCover they−axis. Find the coordinates of the image.
To reflect 4 ABCover they−axis they−coordinates will remain the same. Thex−coordinates will be the same
distance away from they−axis, but on the other side of they−axis.