Warm Up Which of the following is NOT a rigid transformation (or isometry) of the image below: a. b. C. d.
Announcements Quiz on Friday
Rotation Rotation: the spinning of a figure or point around one central point. Described by the amount of degrees the figure is spun. We call this the degree of the rotation.
Under a Rotation Therefore a rotation is a rigid transformation or an isometry
Functional Notation Functional notation A 90 rotation is described by:f(x,y) = (-y,x) A 180 rotation is described by:f(x,y) = (-x,-y) A 270 rotation is described by:F(x,y) = (y,-x)
A transformation is described by f(x,y) = (-y, x). 1. Is this a rotation of 90, 180, or 270 degrees? 2. Under this rotation, the image of (5,2) is _________.
EX. If A(3,-6) A(-6,-3), what is the degree of rotation?
Dilations angle measure is congruent distance (or length) is not congruent NOT RIGID→ NOT ISOMETRIES Represented by the equations (x,y) → (x’, y’) where x’ = kx and y’ = ky and k is constant Two types –contractions and expansions Fixed points-only at the origin
Contraction Reduce_the original figure proportionally Contractions-when 0< k<1
Find the image of the given point under the transformation described by f(x,y) = ((2/3)x, (2/3)y) (6,6) (-12, -3)
Expansion E nlarges the original figure proportionally Expansions-when k>1
Find the image of the given point under the transformation described by f(x,y) = ((2)x, (2)y) (6,6) (-8, -3)
Name the kind of transformation represented by each. 1. (x,y) → (5x, 5y) 2. (x,y) → ((1/4)x, (1/4)y)
Scale Factor
Homework Journal Pg. 286 and Pg. 310