We can describe angles in plane shapes by seeing if they make a square corner, to make a right angle. We can also compare them to right angles to see if they are less than, or greater than a right angle. An angle is formed by two rays that share an endpoint. A vertex is the point where two rays of an angle or two line segments meet in a plane shape, or where three or more edges meet in a solid shape.Vertices is the plural of vertex. A right angle forms a square corner. Changing the position of an angle will not change the size of the angle. We can use the corner of a sheet of paper to help us decide if an angle is a right angle, or not. We count how many angles are in a given shape and if they are right angles, less than right, or greater than right. A little box inside an angle tells us it is a right angle. The little box is a math symbol for a right angle. We identify angles that do not have a right angle.

3rd Grade Math 12.1, Describe Plane Shapes, 2D
   • 3rd Grade Math 12.1, Describe Plane S...  

3rd Grade Math Playlist (2015)
   • 3rd Grade Math Course  

I'm using the Houghton Mifflin Go Math!
2015 copyright textbook for this playlist.

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