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A straight path that goes on forever in both directions. Named using two points on the line. A line has arrows on both ends that show it keeps going.
A part of a line that has two endpoints. A line segment is named using the two endpoints.
A ray has an endpoint on one side and keeps going forever on the other. You always name a Ray using the endpoint first.
A flat surface that keeps spreading in all directions forever. Must be named by three points on the plane.
Two lines, that lie next to each other without ever getting close together or further apart.
An angle that measures less than 90 degrees. (Babies are small, babies are cute. An acute angle is small like a baby)
An angle that is more than 90 degrees. (Obtuse can also mean slow. An obtuse angle is a big, slow angle.)
Two shapes are congruent when all of the sides and angles of the two shapes are exactly the same. The object can be rotated and face a different direction, but the measurements must be the same.
The angles and the overall appearance of the shapes are the same, but one object is larger than the other.
Any object made of at least three straight lines. There can be no gaps, no curves, and no lines that cross each other.
A line segment that joins two vertices of a shape by going through the middle of the shape.
Center (of a circle)
A point in the middle of a circle that is the same distance from outside of the circle all the way around.
A line segment that goes from one side of the circle to the other and passes through the center of the circle.
A line segment that goes from one side of the circle to the other side. A chord does not have to go through the center.
If an object can have a line drawn down the center and both sides are congruent, then the object has line symmetry.
If you can rotate an object less than 360 degrees and the object looks like it did before you turned it, then the object has rotational symmetry.
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