# Miss Pancoe and Miss Reuter's Chapter 4--Geometry

## 44 terms · 4th grade geometry terms

### point

An exact location in space

### line segment

Part of a line consisting of two fixed points and all of the points between them

### line

An infinite set of points in opposite directions forming a straight path

### ray

Part of a line that has one endpoint and extends infinitely in one direction

### endpoint

A point at either end of a line segment or the beginning point of a ray

### horizontal

Parallel to or in the plane of the horizon

### vertical

Straight up and down; perpendicular to the horizon

### intersecting lines

Lines that share a common point

### parallel lines

Lines in the same plane that never intersect no matter how far they are extended

### perpendicular lines

Two lines that intersect to form right angles

### angle

A geometric figure formed by two rays that have a common endpoint

### acute angle

An angle whose measure is greater than 0° and less than 90°

### obtuse angle

An angle whose measure is greater than 90° and less than 180°

### right angle

An angle formed by two perpendicular lines, the measure of which is 90°

### straight angle

An angle that has a measure of 180°

### reflex angle

An angle that has a measure greater than 180°

### congruent figures

Two or more figures having exactly the same shape and size

### similar figures

Figures that have the same shape but not necessarily the same size

### polygon

A closed plane figure formed by three or more line segments

### triangle

A polygon with three sides and three angles

A polygon with 4 sides and 4 angles

### pentagon

A polygon with 5 sides and 5 angles

### hexagon

A polygon with six sides and six angles

### octagon

A polygon with 8 sides and 8 angles

### trapezoid

A quadrilateral with exactly one pair of parallel sides

### kite

A quadrilateral with no parallel sides and two pairs of equal sides

### parallelogram

A quadrilateral with two pairs of parallel sides

### rectangle

A quadrilateral with four right angles

### rhombus

A parallelogram with all four sides congruent

### square

A rectangle with all four sides congruent

### circle

A plane closed curve consisting of all points a fixed distance from a fixed point called its center

### flip (reflection)

A transformation when a geometric figure is flipped over a line to obtain a mirror image

### slide (translation)

A transformation where every point moves the same distance in one or two directions

### turn (rotation)

A transformation when a geometric figure is rotated about a fixed point

### open figure

A figure that is not closed

### closed figure

A figure that starts and ends at the same point

### regular polygon

A shape in which all sides and all angles are congruent

### symmetry

The property of having the same size and shape across a dividing line

### plane figure

A figure that lies on a flat surface

### geometric figure

Any combination of points, lines, planes, or curves in two or three dimensions

### two-dimensional figure

A figure that has length and width but no height (Example- circle, square, triangle)

### vertex

1)The common endpoint of two sides of a polygon; (2) the common endpoint of two rays that form an angle; (3) the common point where two or more edges of a three-dimensional solid meet

### vertices

The plural form of vertex

### side

A line segment joining two adjacent vertices of a polygon