# Chapter 9 Math

## 67 terms · Geometry Vacabulary

### Point

An exact location in space

### Ray

Part of a line with one endpoint, extending forever in only one direction

### Plane

A flat surfact that extends forever in all directions

### Parallel Lines

Are in the same plane but do not intersect

### Skew Lines

Lie in different planes. They don not intersect and are not parallel

### Protractor

an instrument for drawing/measuring angles

### Acute Angle

Between 0 and 89 degrees

### Line

Straight path of points that goes on forever in two directions

### Line Segment

Part of a line with two endpoints

### Congruent Line Segments

Line segments with the same length

### Intersecting Lines

Pass through the same point

### Perpendicular Lines

Intersecting lines that form right angles

### Angle

Formed by two rays that have the same endpoint, measured in degrees

### Vertex

The point on the angle where the two rays meet

### Right Angle

Exactly 90 degrees

6 sided polygon

8 sided polygon

10 sided polygon

### Diagnal

A line segment that connects two vertices of a polygon and is not a side

### Acute Triangle

All three angles are acute angles

### Obtuse Triangle

One angle is an obtuse angle

### Isosceles Triangle

At least two sides are congruent

### Trapezoid

Is a quadrilateral with only one pair of parallel sides

7 sided polygon

9 sided polygon

12 sided polygon

### Regular Polygon

Has sides of equal length and angles of equal measure

### Right Triangle

One angle is a right angle

### Equilateral Triangle

All sides are congruent

### Scalene Triangle

No sides are congruent

### Parallelogram

A quadrilateral with both pairs of opposite sides parallel. Opposite sides as well as opposite angles are congruent

### Obtuse Angle

Between 91 and 179 degrees

### Congruent Angles

Have the same measure (arcs are show drawn inside the angles to show congruent angles)

A pair of angles with a common vertex and a common side but no common interior points

### Supplementary Angles

Two angles whose measures add up to 180 degrees

### Arc

A part of a circle drawn with a compass

### Angle Bisector

A ray that splits an angle into two congruent angles

### Polygon

A closed plane figure made up of line segments

4 sided polygon

### Straight Angle

Exactly 180 degrees

### Verticle Angle

A pair of angles formed by intersecting lines (they have no side in common and vertical angles are congruent)

### Complementary Angles

Two angles whose measures add up to 90 degrees

### Construction

A geometric drawing made with just 2 tools, an unmarked ruler and compass

### Perpendicular Bisector

A line, ray, or segment that intersects a segment at its midpoint and is perpendicular to it

### Vertex

The endpoint of an angle bisector

3 sided polygon

5 sided polygon

### Rhombus

A parallelogram with all sides congruent

### Square

A rectangle with all sides congruent, a square is also a rhombus

Any line segment that connects the center to a point on the circle

### Chord

Any line segment that connects two points on the circle

### Semicircle

An arc that connects the endpoints of a diameter

### Similar Figures

Same shape but not the same size

### Flip or Reflection

Figure gives its mirror image over a line

### Rectangle

A parallelogram with four right angles

### Circle

Closed plane figure made up of all the points the same distance from the center

### Diameter

Any line segment through the center that connects two points on the circle

### Central Angle

An angle whose vertex is the center

### Sector

A region bounded by two radii and and arc

### Congruent figures

Same size, Same shape

### Slide of Translation

Move a figure in a straight direction

### Glide Reflection

A slide followed by a flip

### Turn or rotation

Moves a figure about a point

### Line of Symmetry

The line of reflection

### Tesselation

A pattern of congruent figures that fills the plane without gaps or overlaps

### Reflection Symmetry

It can be reflected on itself

### Rotational Symmetry

When a figure rotates itself in less than a full turn