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Hi, everybody.
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We're in section 8 .1, and we're going to do problem number two.
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And they give us two triangles, and they want to know these two triangles are similar.
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They tell us that they're similar.
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So let's draw the triangles.
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We have triangle a, b, c, and we have a smaller one that's triangle d, e, f.
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And they told us that triangle abc is similar to triangle def.
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They also told us the side lengths.
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So we have ac is 12.
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We have bc is 16.
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A .b is 20.
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D .f is 3.
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E .f is 4 and de is 5.
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So the question is they tell us a lot of vocabulary and they want to know what's different.
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So first thing we're going to talk about is the scale factor.
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So we'll make that a.
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We'll call this the scale factor.
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What is the scale factor? well, when you have similar triangles or any similar polygons, we look at the ratio of one side to its corresponding side and the other triangle.
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For example, we can say bc over ef, 16 to 4, or 12 to 3, or 20 to 5.
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All of these, right, no matter which we do, are going to reduce, right, 16 to 4 or 12 to 3 or 20 to 5, they all reduce to a ratio of 4 to 1...