Download Chapter 1 Vocabulary Geometry 2015 Sec 1-1 Points

Chapter 1 Vocabulary
Geometry 2015
Sec 1-1 Points, Lines and Planes
1. Undefined terms – point, line and plane. They are only explained using examples and
descriptions.
2. Point – a location. Has neither shape nor size. It is named using a capital letter. A point
has no dimension.
3. Line – made up of points and has no thickness or width. There is exactly one line
through any two points. It is named by using two points on the line or a lowercase
cursive letter. A line has 1-dimension.
4. Plane – a flat surface made up of points that extend infinitely in all directions. There is
exactly one plane through any 3 points not on the same line. It is named using a capital
cursive letter or any 3 points that are not on the same line.
5. Collinear – points that lie on the same line.
6. Noncollinear – points that do NOT lie on the same line.
7. Coplanar – points that lie in the same plane.
8. Noncoplanar – points that do not lie in the same plane.
***The prefix “co” means together. The prefix “non” means not. ****
9. Intersection – a set of points common to two or more geometric figures.
10. Space - a boundless, 3-dimensional set of all points. Space can contain lines and
planes.
Sec 1-2 Line Segments and Distance
11. Line segment – a piece of a line with two endpoints. A line segment is named using
two capital letters for the endpoints.
12. Congruent – Two or geometric figures that have the same shape and size. The symbol
for congruent is ≅.
13. Rigid Transformation – a transformation in which the position of the image may be
different from the preimage, but the two figures remain congruent.
14. Congruent segments – Two segments that have the same measure.
15. Constructions – methods of creating figures without the benefit of measuring tools.
16. Distance between two points – the length of the segment between two points.
17. Irrational number – a number that cannot be expressed as a terminating or repeating
decimal.
Sec. 1-3 Locating Points and Midpoints
18. Midpoint (of a segment) - is the point halfway between the endpoints of a segment.
19. Segment bisector – Any segment, line or plane that intersects a segment at its
midpoint.
Sec 1-4 Angle Measure
20. Ray - part of a line with one endpoint and extending indefinitely in one direction. Rays
are named by using the endpoint and any other point on the ray.
21. Opposite rays – two rays that share an endpoint and extend in opposite directions.
Opposite rays are collinear.
22. Angle – two noncollinear rays that have a common endpoint.
23. Sides of an angle – Formed by two rays that share an endpoint
24. Vertex – The common endpoint of an angle;
25. Right angle – An angle that measures exactly 90°
26. Acute angle – An angle measuring between 0° and 90°.
27. Obtuse angle – An angle measuring greater than 90° and less than 180°.
28. Straight angle – An angle measuring exactly 180°.
29. Congruent Angles – Angles having the same measure.
30. Angle bisector – A ray that divides an angle into two congruent angles.
****MIDCHAPTER VOCAB QUIZ *************************************************
Sec 1-5 Angle Relationships
31. Adjacent angles – Angles that lie in the same plane and have a common vertex and a
common side, but no common exterior points.
32. Linear pair – a pair of adjacent angles with noncommon sides that are opposite rays.
33. Vertical angles – two nonadjacent angles formed by two intersecting lines. The two
angles share only a vertex.
34. Complementary angles – Two angles with measures that have a sum of 90°.
35. Supplementary angles - Two angles with measures that have a sum of 180°.
36. Perpendicular - lines, segments or rays that intersect to form right angles.
***You cannot assume geometric relationships of figures in a diagram. Just because two
angles LOOK like they are congruent, does not necessarily mean that they are congruent.
Sec 1-6 Two Dimensional Figures
37. Polygon - A closed figure formed by three or more segments such that each segment
intersects exactly two other segments at their endpoints and no two segments with a
common endpoint are collinear.
38. Vertex of a polygon – the intersection of two sides of a polygon
39. Concave – a polygon in which a diagonal can be drawn so that part of the diagonal
contains points in the exterior of the polygon.
40. Convex – a poygon in which no diagonal contains points in the exterior of the polygon
41. N-gon – an n-sided polygon
42. Equilateral polygon – a polygon in which all sides are congruent
43. Equiangular polygon – a polygon in which all angles are congruent
44. Regular polygon – a polygon that is both equilateral and equiangular
45. Perimeter – the sum of the lengths of the sides of the polygons. The word “perimeter”
comes from the Greek “peri” which means around and “meter” which means measure.
46. Circumference – the distance around a circle.
47. Area – the number of square units needed to cover a surface
Sec 1-7 Three-Dimensional Figures
48. Polyhedron – a closed 3-dimensional figure formed by 4 or more polygons that
intersect only at their edges
49. Face – the flat surface of a solid
50. Edge – the segments where the faces of a solid intersect
51. Vertex - the point where 3 or more edges intersect
52. Prism - a polyhedron with 2 parallel congruent faces called bases, connected by
parallelogram faces
53. Base – one of the two congruent parallel faces of a prism
54. Pyramid – a polyhedron that has a polygonal base and 3 or more triangular faces that
meet at a common vertex
55. Cylinder – a solid with congruent parallel circular bases connect by a curved surface
56. Cone – a solid with a circular base connected by a curved surface to a single vertex
57. Sphere – a set of points in space that are the same distance from a given point. A
sphere has no faces, edges or vertices.
58. Regular polyhedron – a polyhedron with faces that are all regular congruent polygons
and all of the edges are congruent
59. Platonic solid – one of five regular polyhedral: a tetrahedron, a cube, an octahedron, a
dodecahedron or an icosahedron. They are called this because Plato used them
extensively.
60. Surface area – a 2-dimensional measurement of the surface of a solid figure.
61. Volume – the measure of the amount of space enclosed by a solid figure