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No Clickers. Bellwork. Find the geometric mean of 5 & 18 Find the geometric mean of 3 & 44 Solve for x Solve for x, if AB & CD are parallel What point is twice as far from the origin as (3, 5)?. 5. 3. x. x-2. 2x-1. C. A. x. 8. B. 12. D. Bellwork Solution.
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No Clickers Bellwork • Find the geometric mean of 5 & 18 • Find the geometric mean of 3 & 44 • Solve for x • Solve for x, if AB & CD are parallel • What point is twice as far from the origin as (3, 5)? 5 3 x x-2 2x-1 C A x 8 B 12 D
Bellwork Solution • Find the geometric mean of 5 & 18
Bellwork Solution • Find the geometric mean of 3 & 44
Bellwork Solution • Solve for x 5 3 x x-2
Bellwork Solution C • Solve for x, if AB & CD are parallel A x 2x-1 8 12 B D
Bellwork Solution • What point is twice as far from the origin as (3, 5)?
Perform Similiarity Transformations Section 6.7
The Concept • We’ve covered most of chapter 6, but we have yet to apply our understanding of similarity to objects on the coordinate plane. • Today we’re going to use our understanding of similarity and transformations to discuss similarity transformations.
Review • We’ve seen three kinds of transformations thus far • Translations • Shifts or moves up or down and right or left • Rotations • Object rotations a direction and angle about the origin • Reflections • Flips of an object either over the x-axis or the y-axis • The last one that we will learn about is dilations
Definitions • Dilation • Special kind of transformation that stretches or shrinks a figure to create a similar figure • Figures are either reduced or enlarged • Type of similarity transformation
Definitions • Center of Dilation • Fixed point with which the object is dilated • Scale factor of dilation • Ratio of a side length of the image to the corresponding side length of the original figure
Coordinate Notation • We prefer to be able to notate for dilations • For dilations centered at the origin • (x,y)(kx,ky), where k is a scale factor • If 0<k<1, reduction • If k>1, enlargement
Drawing a Dilation • Draw a dilation of an object with vertices (0,2), (5, 3) & (5,-3) using a scale factor of 2
Drawing a Dilation • Draw a dilation of an object with vertices (4,6), (2, 4) & (6,-6) using a scale factor of 1/2
Example Draw a dilation of a quadrilateral ABCD with vertices A(2,2), B(4,2), C(4,0), D(0,-2). Use a scale factor of 1.5 and label the object FGHJ
Scale or k factor • We’ve discussed scale factor before and defined it as • The quotient of a side length of the second object and the corresponding side length of the first object • This property of dilations is no different • For example, find the scale factor of these two objects 2 1
Example • We can also determine k factor from points • Find the k factor between these two objects What do we need in order to give an accurate answer
Example • Is the green object a dilation of the yellow one? How do we know?
Practical Example • You are using a photo quality printer to enlarge a digital picture. The picture on the computer screen is 6 centimeters by 6 centimeters. The printed image is 15 cm by 15 cm. What is the scale factor of the enlargement?
Homework • 6.7 Exercises • 1, 2-8 even, 9-23, 25, 26
Example Draw a dilation of a quadrilateral ABCD with vertices A(-3,5), B(3,4), C(4,-2), D(-3,-2). Use a scale factor of 1.5 and label the object FGHJ
Most Important Points • Definition of Dilation • Bounds for the k scalar • Performing Dilations • Finding k factor from points