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# Geo - Unit 1 vocab

Term | Definition |
---|---|

Point | Indicates a location and has no size or shape. |

Line | Is made up of infinitely many points and has no thickness or width. there is exactly one of these through any 2 points. |

Plane | A flat surface made up of points that extend infinitely in all directions. There is exactly 1 of these through any 3 points. |

Collinear points | Points that lie on the same line |

Coplanar points | Points that lie on the same plane. |

Intersection | Two or more geometric figures and the set of points they have in common. |

Space | Defined as the boundless, three-dimensional set of all points; can contain lines and planes. |

Skew lines | Lines that are non-coplanar and do not intersect. |

Line segment | Can be measured because it has 2 endpoints which can be used to name it. |

Betweenness of points | For any real numbers a and b, there is another real number between a and b such that a < n < b. This relationship also applies to points on a line. |

Segment addition postulate | If three points A, B, and C are collinear and B is between A and C, then AB + BC = AC. |

Congruent | When two geometric figures have exactly the same size and shape. |

Congruent segments | When one segment can be mapped onto another segment. |

Ray | A part of a line that consists of one endpoint and all the points of the line on 1 side of the endpoint. |

Opposite rays | Two rays that share the same end point and form a line. |

Absolute value | The distance between two points on a number line. |

Pythagoream theorem | a^2 + b^2 = c^2 |

Midpoint | (of a segment) A point that divides the segment into 2 congruent segments; this point will be halfway between the two endpoints. |

Segment bisector | A point, line, ray, or other segment that intersects a segment at its midpoint. |

Angle | Formed by two rays that have the same endpoint. |

Inside | When a point is located in the interior of an angle. |

Outside | When a point is located on the exterior of an angle. |

On | When a point is in contact with one of the angle's rays. |

Acute angle | An angle with a measurement more than 0 but less than 90. |

Right angle | An angle with a measuremnt of 90 degrees. |

Obtuse angle | An angle with a mesurement more than 90 but less than 180. |

Straight angle | An angle with a measurement of 180 degrees. |

Congruent angles | Angles with the same measure. |

Angle bisector | A ray that divides an angle into two congruent angles. |

Angle addition postulate | When a line/segment/ray divides and angle into smaller angles, the sum of the measures of the smaller angles, equal the measure of the larger angle. |

Ajacent angles | Two coplanar angles with a common side, a common vertex, and no common interior points. |

Linear pair | A pair of ajacent angles whose noncommon sides are opposite rays. |

Vertical angles | Two nonadjacent angles formed by intersecting lines; these angles are congruent. |

Complementary angles | Two angles whose measures have a sum of 90 degrees. |

Supplementary angles | Two angles whose measures have a sum of 180 degrees. |

Perpendicular | When a line, segment, or ray forms a right angles. |

Polygon | A closed plane figure formed by 3 or more segments. |

Triangles | Polygons with 3 sides. |

Quadilaterals | Polygons with 4 sides. |

Pentagons | Polygons with 5 sides. |

Hexagons | Polygons with 6 sides. |

Heptagons | Polygons with 7 sides. |

Octogons | Polygons with 8 sides. |

Nonagons | Polygons with 9 sides. |

Decagons | Polygons with 10 sides. |

Hendecgons | Polygons with 11 sides. |

Dodecagons | Polygons with 12 sides. |

N-gons | Polygons with 13 or more sides. |

Diagonal | A segment that connects two nonsecutive vertices |

Convex polygon | A polygon with no diagonal with points outside the polygon. |

Concave polygon | A polygon with at least 1 diagonal with points outside of the polygon. |

Equilateral polygon | A polygon in which all sides are congruent. |

Equiangular | A polygon in which all angles are congruent. |

Regular polygon | A convex polygon that is both equilateral and equiangular. |

Irregular polygon | A polygon that is not regular. |

Perimeter | (of a polygon) The sum of the lengths of its sides. |

Area | (of a polygon) the number of square units it encloses, found by multiplication. |

Circumference | The perimeter of a circle. |

P=4s | The formula for the perimeter of a square. |

A=s^2 | The formula for the Area of a square. |

P=2(l+w) | The formula for the perimeter of a rectangle. |

A=lw | The formula for the Area of a reactangle. |

P=a+c+b | The formula for the perimeter of a triangle. |

A=1/2bh | The formula for the area of a triangle. |

c=2pir | The formula for the circumference of a circle. |

Polyhedron | A space figure, or 3 dimensional figure whose surfaces are polygons. |

Face | Each polygon that makes a polyhedron. |

Edge | A segment that is formed by the insection of two faces |

Vertex | (of a polygon)A point where 3 or more edges intersect. |

Surface area | A two-dimensional meaurement of the area of a solid figure. |

Volume | The measure of the amount of space enclosed by a solid figure. |

v=Bh | The formula for the volume of a right prism. |

v=Bh | The formula for the volume of a right cylinder. |

v=1/3Bh | The formula for the volume of a Regular pyramid. |

v=1/3Bh | The formula for the volume of a Right cone. |

v=4/3pir^3 | The formula for the volume of a sphere. |

Net | A two-dimensional representation of a 3D object. |

Transformation | A function that maps a figure, the preimage, onto a new figure called the image. |

Preimage | The figure before it is translated. |

Image | The figure after it is translated. |