9 6 Dilations A dilation is an enlargement

9. 6: Dilations

A dilation is an enlargement if the scale factor is greater than 1 and a reduction if the scale factor is between 0 and 1.

What is the scale factor?

What is the scale factor?

For us…center of dilation is always the origin

What would the new vertices of this image be after a dilation with scale factor 2?

What would the new vertices of this image be after a dilation with scale factor 1/2?

19. The image of a button is 6 cm across and 5 times actual size…what is the actual size of the button?

Break time

9. 7: Similarity Transformations

What is the series of transformations to bring RST to PYZ?

What is the series of transformations to bring ABCD to NMPH?

A similarity transformation is a composition of rigid motions and/or dilations Two figures are similar if and only if there is a similarity transformation from one figure to the other

Why does it work? Are angles congruent? Is there a consistent scale factor?

Are these circles similar? Assume G has a radius of 15 and H has a radius of 12

Are ALL circles similar?

Is there a similarity transformation from PAQ to TNO? Not enough information?

What if the shapes aren’t polygons?

Homework: Section 9. 6, pages 590 -591: 7 -9, 16, 17, 19 Honors: Section Add 36 9. 7, pages 598 -599: 8, 9, 11 -13, 15 Honors: Add 17, 18

9. 7