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 * //__The Basics of Geometry__//

[|Geometry help link]

__Basics of [|geomtetry]__** Point- has no demensions. Lines- has one demension it measures length, and it goes on forever and ever. Planes- has two demension, it measures length and width. Has to have at least three point to be a plane. Points, lines, planes are considered undefined terms. Colinear- is a single line that contains two points. Coplanar- a plane that contains at least three points. Segment- a line that has two endpoints. With two endpoints. Endpoints- two points that end at a segment. Ray- is a part of a line with an endpoint on one end and going on infinite. Endpoint- a point of a ray. Angle- has two rays connecting at a common end point. Vertex of the angle- the common end point of an angle. Where two rays connect at a common endpoint. Sides of an angle- the two rays that make up the angle. Interior- The inside of an angle Exterior- The outside of an angle Intersect-To have one or more points in common Intersection-When two or more geometric figures have a point in common Postulates- A true statement without a proof Postulates: The intersection of two lines is a point. The intersection of two planes is a line. Through any two points there is exactly one line. Through any three noncollinear points there is exactly one plane. If two points are in a plane, then the line containing them is in the plane.

A number line- a line that has been set up to correspond with real numbers. Coordinate of a point- a real number on the number line Length- the measurement of two points. The measurement of segment AB. Segment Congruence Postulate- If you have two segments with the same length, the segments are cnsidered congruent. Segment Addition Postulate- Adding two segments together.
 * [[image:butterflyforwikichapter1.jpg width="87" height="72" link="http://www.flickr.com/photos/malfalfa/1349529877/"]]Measuring Length**

[|Measuring Angles] Degree- The most common unit of angle measurement. Measure of an angle- The vertex is placed at the center of a half of a circle between 0° and 180°. Angle congruence postulate- Two angles that have the same angle measurement. Complementry angles- Two angles add up to be 90°. Complement- The other angle that adds together with another angle to measure 90°. Supplementry angles- Two angles that add up to be 180°. Supplement- The other angle that adds together with another angle to measure 180°. Linear pair- An endpoint of a ray falls on a line to form two angles that will add up to be 180°. Linear pair property- Two angles that create a linear pair is a supplementry angle. Right angle- An angle that measures 90°. Acute angle- An angle that measures less than 90°. Obtuse angle- An angle that measure more than 90° and less 180°.

Constructions- Something created under certain rules and is considered mathamatically precise. Perpendicular line- Two lines that intersect to form a right angle. Parallel lines- two coplaner lines that never intersect. Paralle lines go on forever without touching. Conjecture- A statement that you believe to be true or a guess that is based on observation. Segment bisector- A line in which divides a segment into two congruent parts. Midpoint- The bisector intersects the segment. It is located the exact middle if the segment. Perpendicuar bisector- A line that divides a segment into two congruent parts. It is the line that intersects the segment, forming a right angle. Angle bisector- A line or ray divides and angle into two congruent angles.
 * [[image:butterflyforwikichapter1.jpg link="http://www.flickr.com/photos/malfalfa/1349529877/"]]The basics of [|paper folding]**

Inscribed circle- A circle within a triangle that touches all three sides of the triangle. Circumscribed circle- A circle surrounding a triangle containing all three vertices. Concurrent- Three or more lines interecting at a single point. Incenter- The center of an inscribed circle. To find the center of the inscribed circle you find the angle bisector of each angle in the triangle. Circumcenter- The center of a circumscribed circle. To find the center of a circumscribed circle you find the perpendicular bisector of each side of the triangle.
 * [[image:butterflyforwikichapter1.jpg width="94" height="80" link="http://www.flickr.com/photos/malfalfa/1349529877/"]]Special points on a triangle**

[|Motion] Rigid Transformations- transformations that do not change the size or shapeof a figure. Preimage- A shape that undergoes a motion or transformation. Image- A shape that results from a transformation of a figure or preimage. [|Translation]- Every point of the preimage moves in the same direction by the same amount to form the image Rotation- every point of the preimage is rotated by a given angle about a poin( in two dimensions) or a line (in three dimensions.) Center of Rotation- All points move the same angle measure. Reflection- Every point of the preimage is moved across a line or the mirror line so that the mirror is the perpendiculaer bisector of the segment connectiing the point and its image.

Horizontal translation of //h// units: H (x,y) = (x + 0, y) Vertical translation of //v// units: V (x,y)= (x,y + 0) Reflection across the x- axis: M (x,y)= (x,y - 0) Reflection across the y- axis: N (x,y)= x- 0,y) 180° Rotation About the Origin: R (x,y)= (x - 0, y-0)
 * [[image:butterflyforwikichapter1.jpg width="95" height="81" link="http://www.flickr.com/photos/malfalfa/1349529877/"]]Motion in the coordinate plane**