Geometry Basics

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Point

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An undefined term in geometry, it names a location and has no size

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Line

Back 2

An undefined term in geometry, a line is a straight path that has thickness and extends forever

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Plane

Back 3

An undefined term in geometry, it is a flat surface that has no thickness and extends forever

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Collinear

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Points that lie on the same line

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Coplanar

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Points that lie the same plane

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Postulate (axiom)

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A statement that is accepted as true without proof.Also called an axiom

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Segment of a line

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A part of a line consisting of two endpoint sand all points between them

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Endpoint

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A point at an end of a segment or the standing point of a ray

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Ray

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A part of a line that starts at an endpoint and extends forever in one direction

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Opposite Rays

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Two rays that have a common endpoint and form a line

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Congruent

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Having the same size or shape

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Midpoint

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The point that divides a segment into two congruent segments

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Segment bisector

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A line, ray, or segment that divides a segment into two congruent segments

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Side of a polygon

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One of the segments that from a polygon

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Vertex of a polygon

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The intersection of two sides of the polygon

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Diagonal

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A segment that connects any two non consecutive vertices

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Regular polygon

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Polygon that is both equilateral and equiangular

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Concave

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Any part of the diagonal contains point in the exterior of the polygon

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Convex

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No diagonal contains points in the exterior

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Vertex

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It's a corner of an shapes or angles

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Angle bisector

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That divides an angle into two congruent angles

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Adjacent angle

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Two angles in the same plane with a common vertex and a common side, but no comment interior points

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Vertical angles

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Nonadjacent angles formed by two interesting lines

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Linear pair

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A pair that adjacent angles whose non common sides are opposite rays

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Complementary

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Two angles whose measures have a sum of 90'

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Supplementary

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Two angles whose measure have a sum of 180'

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Perpendicular

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Intersecting to form 90' angles

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Polygon

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A closed plane figure formed by three or more segments such that each segment intersects exactly two other segments only at their end points and no two segments with a common endpoint are collinear

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Perimeter

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The sum of the side lengths of a closed plane figure

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Perimeter

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The sum of the side lengths of a closed plane figure

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Angle

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A figure formed by two rays with a common endpoint

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Theorem

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A statement that has been proved

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Theorem

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A statement that has been proved

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Proof

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An argument that uses logic to show that a conclusion is true

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Theorem

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A statement that has been proved

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Proof

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An argument that uses logic to show that a conclusion is true

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Inductive reasoning

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The process of reasoning that a rule or statement that a rule or statement is true because specific cases are true

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Theorem

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A statement that has been proved

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Proof

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An argument that uses logic to show that a conclusion is true

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Inductive reasoning

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The process of reasoning that a rule or statement that a rule or statement is true because specific cases are true

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Counter example

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An example that proves that a conjecture or statement is false