##### Vocabulary Geometry

point

an exact location in space

acute angle

an angle that is less than 90 degrees and smaller than a right angle

Hexagon

a polygon with 6 sides and 6 vertices

intersecting lines

the 2 line segments cross each other at a point

parallel lines

lines that are equal distance apart at every point and they never intersect

The strips on the monarch caterpillar are parallel.

symmetric

symmetrical

lines of symmetry

a figure is symmetric if it can be folded into 2 congruent halves that fit on top of each other. The line of symmetry divides the valentine heart into 2 congruent shapes.

line

a straight path of points that goes on forever in both directions

plane

an endless flat surface

perpendicular lines

2 lines that intersect at a right angle

line segment

part of a line that has 2 end points

ray

part of a line that has 1 end point and extends forever in one direction

angle

a figure formed by 2 rays that have the same endpoint

right angle

an angle that measures exactly 90º

obtuse angle

and angle that measures more than 90º

straight angle

an angle that measures exactly 180º

polygon

a closed shape made up of line segments

side

each of the line segments of a polygon

vertex, vertices

the point where 2 rays meet to form an angle. the points where the sides of a polygon meet.

triangle

a polygon with 3 sides and 3 angles

quadrilateral

a polygon with 4 sides and 4 angles

pentagon

a polygon with 5 sides and 5 angles

octagon

a polygon with 8 sides and 8 angles

parallelogram

a quadrilateral in which the opposite sides are parallel

rectangle

a parallelogram with 4 right angles

square

a parallelogram with 4 right angles and all sides the same length

rhombus

a parallelogram with all sides the same length

trapezoid

a quadrilateral with only 1 pair of opposite sides that are parallel

equilateral triangle

a triangle with 3 equal sides

isosceles triangle

a triangle that has 2 equal sides

scalene triangle

a triangle that has no sides that as the same length

right triangle

a triangle with 1 right angle

acute triangle

a triangle with 3 acute angles

obtuse triangle

a triangle with one obtuse angle

congruent

2 shapes that are the same shape and the same size

similar

2 shapes that are the same shape but not the same size

classify

To arrange in groups, by some property.

These shapes are classified by the number of sides.

ellipse

a 2 dimensional shape that resembles a flatten circle

An ellipse has only 2 lines of symmetry

equiangular

two dimensional

a shape that has height and width but no depth, Squares, Circles, Triangles, etc are two dimensional objects

congruent polygons

2 polygons that are the same shape and same size