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CCSS.Math:

which side is perpendicular to side BC so BC is this line segment right over here and for another segment to be perpendicular to it perpendicular just means that the two segments need to intersect at a right angle or at a 90 degree angle and we see that BC intersects a B at a 90 degree angle the symbol right over here represents a 90 degree or a right angle so we just have to find side a B or B a and that's right over here side a B is perpendicular to side BC let's do a few more of these put the triangles in to the correct categories so this right over here so let's see let's think what our categories right triangles so that means it has a 90 degree angle in it obtuse triangles that means it has an angle larger than 90 degree in it 90 degrees in it acute triangles that means all three angles are less than 90 degrees so this one has a 90 degree angle has a right angle right over here so this is a right triangle this one right over here all of these angles are less than 90 degrees just eyeballing it so this is going to be an acute that's going to be an acute triangle I put it under acute triangles right over there then this one over here this angle up here this is U and we can assume that these actually are drawn to scale this is more open than a 90 degree angle this is an obtuse angle right over here it's going to be more than 90 degrees so this is an obtuse this is an obtuse triangle now this one over here all of them seem acute none of them even seem to be a right angle so I would put this again into acute acute triangles this one here clearly has a right angle it's labeled as such so we'll throw it right over here and then this one this angle right over here is clearly even larger has a larger measure than a right angle so this angle right over here is more than 90 degrees it's going to be an obtuse angle so we will throw it into obtuse obtuse triangles so we got two in each of these and let's check our answer and we got it right