# Shared Flashcard Set

## Details

Basic Geometric Terms
Basic Geometric Terms
30
Mathematics
09/06/2011

Term
 point
Definition
 represents a position in space or on a plane has no size represented by a dot   labeled with an upper case letter   . P
Term
 line
Definition
 figure that extends forever in 2 directions NO ENDPOINTS Named with any 2 of its points' letters under a ↔  OR by line and an italiziced letter put near line to name. [image]
Term
 line segment or simply segment
Definition
 part of a line that is between and including 2 endpoints   Named by its 2 endpoints in any order under ‾‾.
Term
 Ray
Definition
 Part of line that is on one side of a point of that line. Named with its initial (or ENDPOINT) FIRST and then any point through which the ray goes under a  →.  [image]
Term
 collinear
Definition
 points that could lie on one line. Here, the red points are collinear, the gray points are noncollinear because they cannot all lie on only 1 line [image]
Term
 intersection
Definition
 the common point or points shared by 2 figures [image] E is the intersection of line AD and line BC. [image]  The blue line is the intersection of plane M and plane S.
Term
 length of segment MJ
Definition
 distance between Points M and J . if on a number line the absolute value of the difference of the coordinates of the endpoints. | coordinate of M minus coordinate of J| Will always be positive or 0. BE CAREFUL WITH NEGATIVES.
Term
Definition
 If C is between A and B, then AC + CB = AB. part segment + other part = entire segment in question [image]
Term
 congruent
Definition
 segments, angles or figures having equal SIZE AND SHAPE.  @  means congruent   Congruent segments are shown on drawings by the same number of tick marks on congruent segments. Congruent angles are shown the same way OR by having the same number of arcs.
Term
 midpoint
Definition
 The point that divides a segment into 2 congruent segments. If M is the midpoint of segment AB [image]  AM = MB
Term
 ANGLE
Definition
 figure formed by 2 rays that share the same initial or endpoint. Rays are the sides, vertex is point shared by both. Angles are named with a single number or the letter for the vertex point if they are isolated. If it is not clear which angle is meant,  3 letters are needed:  the letters for the vertex and a point on each side of the angle.  This angle could be named ÐACB, ÐBCA orÐC
Term
 complete rotation
Definition
 A complete rotation contains 360°. Ancients believed that it took the sun 360 days to circle the earth. Be glad that they did not know that it takes 365 1/4 days for the earth to circle the sun. Degrees measure how open an angle is, not how long the sides are.
Term
 straight angle
Definition
 An angle that forms a straight line with its vertex somewhere on that line. It contains half a rotation or half of 360°. A straight angle contains 180°.[image]
Term
 right angle
Definition
 an angle that contains 1/4 of a complete rotation or 90°. The corner of this index card is a right angle. A square box inside an angle shows that the angle is a right angle. [image]
Term
 acute angle
Definition
 An angle that is more than 0°   and less than 90 ° . [image]   These are cute, little angles.
Term
 obtuse angle
Definition
 An angle that is more than 90° and less than 180 ° [image] This angle is obese or bigger than a right angle, but less than a straight angle.
Term
 distance formula
Definition
 the length between 2 points P1 and P2 on a Cartesian graph. Label the coordinates CAREFULLY ( x1, y1) and (x2, y2).         Then sub into [image]
Term
 midpoint formula
Definition
 If A (x1, y1) and B (x2,y2) are points in a coordinate plane, then the midpoint of line segment AB has the coordinates [image]
Term
 midpoint theorem
Definition
 if M is the midpoint of AB, then            AM = MB = ½  of AB   [image]
Term
 angle bisector
Definition
 a ray that divides an angle into 2 adjacent angles that are congruent ( have equal measures) Ray BD bisects ÐABC since it divides the angle into 2 congruent angles ÐABD and ÐDBC;         mÐABD = mÐDBC [image]
Term
 vertical angles
Definition
 When 2 lines intersect, the 2 pairs of opposite angles are vertical Ðs.  Form BUTTERFLY WINGS or A BOWTIE Ð1 & Ð3are vertical Ðs  ; Ð2 &Ð4 are vertical Ðs [image]
Term
Definition
 If point D is in the interior ofÐABC, then mÐABD + mÐDBC =  mÐABC m partÐ+ m partÐ =m entireÐ [image]
Term
 linear pair
Definition
 the 2 Ðs formed when the endpoint of a ray falls on a line. (2 adjacent Ðs whose noncommon sides are opposite rays.) [image] Ð ADB and ÐBDC form a linear pair and will add to 180° Special case of angle addition.
Term
 complementary angles
Definition
 2 angles whose measures add to 90 o Complementary  Corner   Add to 90o [image]
Term
 supplementary angles
Definition
 two angles whose measures add to 180 degrees. Supplementary make a  Straight Line and/or Add to 180o   [image]
Term
Definition
 angles that share a common vertex and side, but no interior points
Term
 perpendicular lines
Definition
 2 lines that intersect to form right angles. [image] Symbol:  ^  GE ^ DF
Term
 vertical angles theorem
Definition
Term
 midpoint on a number line
Definition
 Add the coordinates of the endpoints. Then, divide that sum by 2 to get the midpoint.   x2 - x1   2
Term
 To find an endpoint when given a midpoint and one endpoint coordinates
Definition
 Label midpoint coordinates (xM  , yM ) Label given endpoint (x1  , y1 ) You are looking for (x2  , y2 )other endpoint [image]
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