Geometry
Vocabulary
1.
1
dimensional figure - an object measured in 1 direction (length)
2.
line
segment - a part of a line with 2 endpoints
3.
line
- a straight path on a plane, that goes on and on in 2 directions
4.
ray
- a part of a line with 1 endpoint that goes on and on in 1 direction
5.
parallel
lines - 2 lines that are the same distance apart
6.
intersecting
lines - lines that cross or meet at exactly 1 point
7.
perpendicular
lines - lines that cross or meet to form right angles
8.
right
angle - measures exactly 90 degrees; a “perfect” corner
9.
acute
angle - smaller than a right angle (“a cute little angle”)
10.
obtuse
angle - larger or open wider than a right angle
11.
2
dimensional figure - an object measured by length and width
12.
plane
figure - a figure that lies on a plane; flat; 2D
13.
circle
- a curved plane figure with each point on the curved line being the same
distance from its center point
14.
polygon
- a closed plane (flat) figure with straight sides
15.
vertex/vertices
- the point where 2 line segments meet in 2D objects, or where 3 faces meet in
3D objects
16.
triangle
- a polygon with 3 sides, angles, angles and vertices
17.
quadrilateral
- any polygon with 4 sides and 4 angles; There are 6 types: square, rectangle,
parallelogram, rhombus, trapezoid, and a general quadrilateral
18.
square
- a polygon with 4 congruent sides and 4 right angles; its opposite sides are
parallel and congruent
19.
rectangle
- a polygon with 4 right angles, whose opposite sides are parallel and
congruent
20.
parallelogram
- a polygon whose opposite sides are parallel and congruent (2 pairs of
parallel sides)
21.
rhombus
- a parallelogram whose 4 sides and opposite angles are congruent
22.
trapezoid
-a quadrilateral with only 1 pair of parallel sides
23.
pentagon
- a polygon with 5 sides, angles, and vertices
24.
hexagon
- a polygon with 6 sides, angles, and vertices
25.
octagon
- a polygon with 8 sides, angles and vertices
26.
symmetry/lines
of symmetry - a figure has a line of symmetry if it can be folded where the
one half is an exact fit on top of the other; a square has 4 lines of symmetry
27.
congruent
- same size and shape
28.
transformation
- the movement of any shape in geometry; 3 types: reflection, translation,
rotation
29.
reflection
- when 1 shape makes the mirror image of another shape; flip
30.
translation
- when 1 shape slides into another position; slide
31.
rotation
- when 1 shape turns around a point; turn
32.
3
dimensional figure - measured in 3 directions: length, width, and height
33.
sphere
- a 3D object with 1 curved surface
34.
face
- the flat surfaces that makes up a 3D figure
35.
edge
- the line segment where 2 faces meet
36.
cube
- a 3D object with 6 congruent square faces
37.
rectangular
prism - a 3D object with 6 rectangular faces
38.
triangular
prism - a 3D object with 2 triangular and 3 rect. faces
39.
pyramid
- ”spear-a-mid” 3 types: square, rectangular, triangular.
40.
cylinder
- has 2 flat faces and 1 curved surface; examples: tissue rolls, cans
41.
cone
- has 1 flat face and 1 curved surface; examples: party hats, ice cream cones