0:00:00.000,0:00:00.670


0:00:00.670,0:00:04.350
Which side is[br]perpendicular to side BC?

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So BC is this line[br]segment right over here.

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And for another segment[br]to be perpendicular to it,

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perpendicular just means[br]that the two segments

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need to intersect at a right[br]angle, or at a 90-degree angle.

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And we see that BC intersects[br]AB at a 90-degree angle.

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This symbol right over here[br]represents a 90-degree,

0:00:24.100,0:00:25.740
or a right angle.

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So we just have to[br]find side AB or BA.

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And that's right over here.

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Side AB is perpendicular[br]to side BC.

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Let's do a few more of these.

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Put the triangles into[br]the correct categories,

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so this right over here.

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So let's see.

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Let's think about[br]our categories.

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Right triangles-- so that means[br]it has a 90-degree angle in it.

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Obtuse triangles-- that[br]means it has an angle larger

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than 90 degrees in it.

0:00:52.920,0:00:55.810
Acute triangles-- that[br]means all three angles

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are less than 90 degrees.

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So this one has a[br]90-degree angle.

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It has a right angle[br]right over here.

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So this is a right triangle.

0:01:04.349,0:01:07.040
This one right over[br]here, all of these angles

0:01:07.040,0:01:10.960
are less than 90 degrees,[br]just eyeballing it.

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So this is going to[br]be an acute-- that's

0:01:13.030,0:01:14.280
going to be an acute triangle.

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I'll put it under acute[br]triangles right over there.

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Then this one over here,[br]this angle up here,

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this is-- and we can[br]assume that these actually

0:01:22.630,0:01:26.564
are drawn to scale, this is more[br]open than a 90-degree angle.

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This is an obtuse[br]angle right over here.

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It's going to be[br]more than 90 degrees.

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So this is an obtuse triangle.

0:01:34.090,0:01:38.030
Now, this one over here,[br]all of them seem acute.

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None of them even seem[br]to be a right angle.

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So I would put this again[br]into acute-- acute triangles.

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This one here clearly[br]has a right angle.

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It's labeled as such.

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So we'll throw it[br]right over here.

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And then this one, this[br]angle right over here

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is clearly even larger.

0:01:54.740,0:01:56.660
It has a larger measure[br]than a right angle.

0:01:56.660,0:01:59.170
So this angle right over[br]here is more than 90 degrees.

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It's going to be[br]an obtuse angle.

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So we will throw it into[br]obtuse-- obtuse triangles.

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So we got two in each of these.

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And let's check our answer.

0:02:12.700,0:02:14.580
We got it right.