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### Course: 7th grade (Illustrative Mathematics) > Unit 1

Lesson 2: Lesson 2: Corresponding parts and scale factors# Identifying corresponding parts of scaled copies

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## Video transcript

- [Instructor] We are told that figure two is a
scaled copy of figure one. And we can verify that by
comparing corresponding sides. Corresponding sides are sides that have the same relative position, the same, they're playing
the same role in each of the diagrams even if the
diagrams are scaled versions of each other, even if
they are different sizes. So for example, if we were to compare segment ea right over here, it looks like it
corresponds to segment op. And the length of ea is three, the length of op is one,
two, three, four, five, six. And so for this to be a scaled copy, the scaling factor from, what from the corresponding
side in figure one to the corresponding side in figure two, should be a factor of two. So it's times two right over there. So let's just answer their
questions that they're asking us, and then we can also verify
that it is a scaled copy. What point on figure one corresponds to the point q on figure two? All right, pause this video and see if you can figure that out. All right, so point q on
figure two is right over there, so what point on figure
one corresponds to that? Well, it would be playing the same role. It would be in the same relative position. And so it looks like this
point right over here, point b, is in that
same relative position. So point b corresponds
to point q on figure two. Identify the side of figure two that corresponds to
segment dc in figure one. Pause this video again and see
if you can figure that out. All right, so segment
dc in figure one, that is that right over there, and your eye might've
immediately catched that hey, the segment that's playing
the same role in figure two is this one right over here. And so that is segment nm. Put the line over it to make sure that I'm specifying the segment. And we can once again verify
the scale factor to ensure that this is a scaled copy. For these two to correspond to each other, and for these to be scaled
copies of each other, dc has a length of one, two, three, four. And nm has a length of one, two, three, four, five, six, seven, eight. So once again, we are verifying that our scale factor is two.