Rigid Transformation - A translation, rotation, or reflection, or a combination thereof., Congruent - Same shape, same size. In terms of a transformation, it is a sequence of translations, rotations and/or reflections that takes the first figure onto the second figure., Reflection - a rigid transformation that takes a point to another point that is the same distance from the given line, is on the other side of the given line, and so that the segment from the original point to the image is perpendicular to the given line., Translation - a rigid transformation that takes a point to another point so that the directed line segment from the original point to the image is parallel to the given line segment and has the same length and direction., Parallel Postulate - Given a line m and a point A that is not on m, there is exactly one line that goes through A that is parallel to m., Parallel - Lines or line segments that don't (and will never) intersect , Circle - The set of all points are at a distance r units from O., Line Segment - A set of points on a line with two endpoints., Perpendicular bisector - a line through the midpoint of a segment that is perpendicular to it, Conjecture - A reasonable guess that you are trying to either prove or disprove., Inscribed polygon - A polygon that fits inside a circle and every vertex of the polygon is on the circle., Inscribed circle - A circle that fits inside the polygon and every side of the polygon is tangent to the circle, angle bisector - a line through the vertex of an angle that divided it into two equal angles, regular polygon - a shape with at least three straight sides and angles. All sides are congruent and all angles are congruent of al, tessellation - an arrangement of figures that covers the entire plane without gaps or overlaps, assertion - a statement that you think is true but you have not proved, image - If a transformation takes A to A', then A is the original and A' is the image., theorem - a statement that has been proved mathematically, directed line segment - a line segment with an arrow at one end specifying a direction, rotation - a transformation that turns a figure about a fixed point called the center of rotation, line of symmetry - a line such that reflection across the line take the figure onto itself, symmetry - an object has symmetry if there is a rigid transformation which takes it onto itself (not counting a transformation that leaves every point where it is), rotation symmetry - a rotation that takes the figure onto itself. (do not count rotations using angle 0° or 360° that leave every point on the figure where it is),