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CCSS.Math:

draw a circle and label the radius diameter Center and circumference let me draw a circle and it won't be that well drawn of a circle but I think you get the idea so that is my circle I'm going to label the center over here so I'll do the center I'll call it C so that is my center and I'll draw an arrow there that is the center of the circle and actually the circle itself is the set of all points that are a fixed distance away from that Center and that fixed distance away that they're all from that center that is the radius so let me draw the radius so this distance right over here is the radius that is the radius and that's going to be the same as this distance which is the same as that distance I can draw multiple radii all of these are radii the distance between the center and any point on the circle now a diameter just goes straight across the circle going through the center from one side of the circle to the other side going through the center and it's essentially two radii put together so for example this would be a diameter that would be a diameter you have one radii then another radii all one line going from one side of the circle to the other going through the center so that is a diameter that is a diameter and I could have drawn it other ways I could have drawn it like this that would be another diameter but they're going to have the exact same length and then finally we have to think about the circumference and the circumference is really just how far you have to go to go around the circle or if you put a string on this circle how long would that string have to be so what I'm tracing out in blue right now the length of what I'm tracing out is the circumference so right over here that is the circumference circumference circumference and we're done