Line reflections

Point ReflectionsReviewMrs. Erickson

ABCBACPoint ReflectionsPoint ReflectionsWhat is preserved?

distance is preserved

angle measure is preserved

midpoint is preserved

collinearity is preservedThe figure is always congruent to its image.Rp = the reflection thru point p

Rp(A)=A the image of A under a reflection in point P is AReflect thru the origin Find A:A (3,5)

Reflect thru the origin Find B:B (-2,4)

yPoint ReflectionsxA (3,5)A (-3,-5)B (-2,4)B (2,-4)Reflect thru the origin Find A:A (-3,2)

Reflect across x-axisFind B:B (-3,2)

Reflect across y-axisFind C:C (-3,2)

yPoint ReflectionsxC (3,2)B (-3,-2)(-3,2)A (3,-2)A reflection in the origin is the same as first reflecting across the x-axis, then across the y-axis.

Point ReflectionsDone!Little Boy: My math teacher is crazy.

Mother: Why?

Little Boy: Yesterday she told us that five is 4+1. Today she is telling us that five is 3+2.