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1026 Lesson 8.notebook
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October 26, 2015
Dec 89:50 PM
Lesson 8: Similarity
Do these figures look similar?
Yes, they look like the same shape, but they are different in size.
How can you prove that they are similar? What would you need to do?
We would need to show that they could become the same size
by dilating one of the figures.
1026 Lesson 8.notebook
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October 26, 2015
Dec 89:50 PM
Lesson 8: Similarity
We could make them the same size, but would a dilation alone map figure S onto S0?No, a dilation alone would not map figure S onto S0
What else should we do to map figure S onto S0?
We would have to perform a translation and a rotation
to map figure S onto S0
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Dec 89:57 PM
Notes:
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October 26, 2015
Dec 810:11 PM
Turn to page S.42
Step 1: Find the scale factor
Step 2: Find the Basic rigid motion or motions.
Step 3: Now use precise language to prove similarity.
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October 26, 2015
Dec 810:15 PM
Since there is no clear way to do this, let's begin with something simplier:
Is there a precise dilation that would make triangle A'B'C' the same as triangle ABC?
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October 26, 2015
Dec 810:20 PM
What scale factor would make A"B"C" the same size as ABC?
r = 2
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October 26, 2015
Dec 810:22 PM
Now that we know how to make triangle A"B"C" the same size as triangle ABC, what rigid motion(s) should we use to actually map triangle A"B"C" onto triangle ABC?
Translate A"'B"'C'" 20 units left and 2 units down
A translation
Let's describe the translation in terms of coordinates.
How many units and in which direction will we need to translate so
that triangle A"'B'"C"' maps onto ABC?
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