Spacial+Thinking



Point**: a location in space that has no size. Adjacent Angles**: angles that share a vertex and a side but no points in their interiors. **Corresponding Angles**: angles that lie on the same side of the transversal and in corresponding positions. Polygon**: a closed plane figure with at least three sides. The sides meet only at their endpoints. Circle**: the set of all points that are the same distance from a given point, called the center of the circle. Perpendicular Lines**: segments or rays that intersect to form right angles. Transformation**: a change of position or size of a figure. Reflectional Symmetry**: a figure has reflectional symmetry when one half is a mirror image of the other half. Rotation**: a transformation that turns a figure about a fixed point.
 * Lesson 9-1
 * Line**: a series of points that extends in two directions without end.
 * Plane**: a flat surface that has no thickness. It continues without end in all directions.
 * Segment**: a part of a line. It has two endpoints. The length of //line PQ// is written as //PQ//.
 * Ray**: a part of a line. It has exactly one endpoint. Name its endpoint first.
 * Parallel**: Two lines that lie in the same plane and do not intersect. You use the symbol ll to indicate "is parallel to". Segments and rays are parallel if they lie in parallel lines.
 * Skew**: lines that do not lie in the same plane. They are not parallel and do not intersect. Skew segments must be part of skew lines.
 * Lesson 9-2
 * Vertical Angles**: angles formed by two intersecting lines and are opposite eachother. Vertical Angles have the same measure.
 * Congruent Angles**: angles that have the same measure.
 * Supplementary Angles**: two angles whose measures sum to 180°.
 * Complementary Angles**: two angles whose measures sum to 90°.
 * Transversal**: a line that intersects two other lines in different points.
 * Alternate Interior Angles**: angles that are in the interior of a pair of lines and on opposite sides of the transversal.
 * Lesson 9-3
 * Regular Polygon**: a polygon that has all sides congruent and all angles congruent. Some regular polygons include Triangles, Squares, Pentagons, and Hexagons.
 * Lesson 9-6
 * Central Angle**: an angle whose vertex is the center of a circle. There are 360 degrees in a circle.
 * Lesson 9-7
 * Segment Bisector**: a line, segment, or ray that divides a segment into two congruent sides.
 * Perpendicular Bisector**: a line, segment, or ray that is perpendicular to the segment it bisects.
 * Angle Bisector**: a ray that divides an angle into two congruent angles.
 * Lesson 9-8
 * Translation**: a transformation that moves points the same distance and in the same direction. A figure and its translated image are congruent.
 * Image**: the figure you get after a translation.
 * Lesson 9-9
 * Line of Symmetry**: a line that divides a figure with reflectional symmetry into two congruent halves. Also called a reflection line.
 * Reflection**: a transformation that flips a figure over a line of reflection.
 * Line of Reflection**: a line in which a figure is reflected over. Also called the line of symmetry.
 * Lesson 9-10
 * Center of Rotation**: the fixed point around which rotation turns a figure.
 * Angle of Rotation**: the angle measure of the rotation.
 * Rotational Symmetry**: a figure has rotational symmetry if the figure can be rotated 180 degrees or less and match the original figure.