Blue Day – 1/16/2015 Gold Day – 1/20/2015

 Find the Rule – Use your yellow cheat sheet from last class 1. M (4,2) was rotated to M’(-4,-2) 2. A (-3,7) was rotated to A’(7,3) 3. P (1,5) was rotated to P’(-5,1)

 Friday, 1/23/2015 is the last day for progress report grades.  Missing grades must be turned in by Tomorrow!!  Transformations Unit test 1/29/2015 & 1/30/2015  Today we will continue transformations  Dialations

Translation, Rotation, and Reflection all change the position of a shape, while the size remains the same. The fourth transformation that we are going to discuss is called dilation.

Dilation changes the size of the shape without changing the shape. DILATION When you go to the eye doctor, they dilate you eyes. Let’s try it by turning off the lights. When you enlarge a photograph or use a copy machine to reduce a map, you are making dilations.

Enlarge means to make a shape bigger. Reduce means to make a shape smaller. The scale factor tells you how much something is enlarged or reduced.

200%50% Notice each time the shape transforms the shape stays the same and only the size changes. ENLARGEREDUCE

Look at the pictures below Dilate the image with a scale factor of 75% Dilate the image with a scale factor of 150%

k > 1 is an enlargement, or expansion. 0< k < 1 is a reduction, or contraction. A scale factor describes how much the figure is enlarged or reduced. For a dilation with scale factor k, you can find the image of a point by multiplying each coordinate by k: (a, b)  (ka, kb).

Copy the figure and the center of dilation P. Draw the image of ∆WXYZ under a dilation with a scale factor of 2. Step 1 Draw a line through P and each vertex. Step 2 On each line, mark twice the distance from P to the vertex. Step 3 Connect the vertices of the image. W’W’ X’X’ Z’Z’ Y’Y’

D: (x, y) → D’(3x, 3y) A(1, 1), B(3, 1), C(3, 2) A’ (3, 3), B’ (9, 3), C’ (9,6)scale factor 3 Apply the dilation D to the polygon with the given vertices. Describe the dilation.

P’(-6, 3), Q’ (-3, 6), R’ (3, 3)scale factor 3/4 D: (x, y) → P(–8, 4), Q(–4, 8), R(4, 4) 4 3 x, 4 3 y B. Apply the dilation D to the polygon with the given vertices. Describe the dilation.