WEBVTT 00:00:00.000 --> 00:00:00.670 00:00:00.670 --> 00:00:04.350 Which side is perpendicular to side BC? 00:00:04.350 --> 00:00:07.720 So BC is this line segment right over here. 00:00:07.720 --> 00:00:10.350 And for another segment to be perpendicular to it, 00:00:10.350 --> 00:00:12.640 perpendicular just means that the two segments 00:00:12.640 --> 00:00:16.540 need to intersect at a right angle, or at a 90-degree angle. 00:00:16.540 --> 00:00:21.640 And we see that BC intersects AB at a 90-degree angle. 00:00:21.640 --> 00:00:24.100 This symbol right over here represents a 90-degree, 00:00:24.100 --> 00:00:25.740 or a right angle. 00:00:25.740 --> 00:00:28.670 So we just have to find side AB or BA. 00:00:28.670 --> 00:00:29.860 And that's right over here. 00:00:29.860 --> 00:00:34.650 Side AB is perpendicular to side BC. 00:00:34.650 --> 00:00:37.530 Let's do a few more of these. 00:00:37.530 --> 00:00:41.690 Put the triangles into the correct categories, 00:00:41.690 --> 00:00:42.940 so this right over here. 00:00:42.940 --> 00:00:43.200 So let's see. 00:00:43.200 --> 00:00:44.575 Let's think about our categories. 00:00:44.575 --> 00:00:47.410 Right triangles-- so that means it has a 90-degree angle in it. 00:00:47.410 --> 00:00:50.590 Obtuse triangles-- that means it has an angle larger 00:00:50.590 --> 00:00:52.920 than 90 degrees in it. 00:00:52.920 --> 00:00:55.810 Acute triangles-- that means all three angles 00:00:55.810 --> 00:00:58.580 are less than 90 degrees. 00:00:58.580 --> 00:01:00.029 So this one has a 90-degree angle. 00:01:00.029 --> 00:01:01.570 It has a right angle right over here. 00:01:01.570 --> 00:01:04.349 So this is a right triangle. 00:01:04.349 --> 00:01:07.040 This one right over here, all of these angles 00:01:07.040 --> 00:01:10.960 are less than 90 degrees, just eyeballing it. 00:01:10.960 --> 00:01:13.030 So this is going to be an acute-- that's 00:01:13.030 --> 00:01:14.280 going to be an acute triangle. 00:01:14.280 --> 00:01:17.080 I'll put it under acute triangles right over there. 00:01:17.080 --> 00:01:19.470 Then this one over here, this angle up here, 00:01:19.470 --> 00:01:22.630 this is-- and we can assume that these actually 00:01:22.630 --> 00:01:26.564 are drawn to scale, this is more open than a 90-degree angle. 00:01:26.564 --> 00:01:28.230 This is an obtuse angle right over here. 00:01:28.230 --> 00:01:30.290 It's going to be more than 90 degrees. 00:01:30.290 --> 00:01:34.090 So this is an obtuse triangle. 00:01:34.090 --> 00:01:38.030 Now, this one over here, all of them seem acute. 00:01:38.030 --> 00:01:40.280 None of them even seem to be a right angle. 00:01:40.280 --> 00:01:46.274 So I would put this again into acute-- acute triangles. 00:01:46.274 --> 00:01:47.940 This one here clearly has a right angle. 00:01:47.940 --> 00:01:49.680 It's labeled as such. 00:01:49.680 --> 00:01:51.600 So we'll throw it right over here. 00:01:51.600 --> 00:01:53.580 And then this one, this angle right over here 00:01:53.580 --> 00:01:54.740 is clearly even larger. 00:01:54.740 --> 00:01:56.660 It has a larger measure than a right angle. 00:01:56.660 --> 00:01:59.170 So this angle right over here is more than 90 degrees. 00:01:59.170 --> 00:02:02.060 It's going to be an obtuse angle. 00:02:02.060 --> 00:02:07.770 So we will throw it into obtuse-- obtuse triangles. 00:02:07.770 --> 00:02:10.810 So we got two in each of these. 00:02:10.810 --> 00:02:12.700 And let's check our answer. 00:02:12.700 --> 00:02:14.580 We got it right.