# GACS lclab - Pre-Algebra 8 - Chapter 9 - Spatial Thinking - Vocabulary

## 20 terms · GACS lclab - Pre-Algebra 8 - Chapter 9 - Spatial Thinking - Vocabulary

two angles that share a vertex and a side but no points in their interiors

### alternate interior angles

angles between two lines and on opposite sides of a transversal

### angle disector

a ray that divides a given angle into two congruent angles, each half the size of the given angle

### complementary angles

two angles whose measure add to 90°

### congruent angles

angles that have the same measure

### congruent figures

figures that have the same size and shape

### corresponding angles

pairs of nonadjacent angles that lie on the same side of a transversal of two lines and in corresponding positions

### parallel lines

lines that lie in the same plane and do not intersect

### perpendicular bisector

a line, segment, or ray that is perpendicular to a segment at its midpoint

### perpendicular lines

lines that intersect to form right angles

### polygon

closed plane figure with at least three sides

### reflection

a transformation that flips a figure over a line of reflection

### regular polygon

a polygon with all its sides congruent and all its angles congruent

### rotation

a transformation that turns a figure about a fixed point, called the center of rotation

part of a line

### segment bisector

a line segment, or ray that separates a segment into two congruent segemnts

### supplementary angles

two angles whose measure add to 180°

### symmetry

divides a figure into two congruent halves

### translation

transformation that moves points the same distance and in the same direction

### vertical angles

angles formed by two intersecting lines, and are opposite each other; these angles are congruent