Math Definitions Chapter 1 Pearson Geometry
Terms
undefined, object
copy deck
 deductive reasoning
 takes known info to get to next step, each fact leads to next conclusion
 inductive reasoning
 base hypothesis on what is seen so far
 collinear points
 points that are on the same line
 coplanar points
 points that are on the same plane
 space
 set of all points
 postulates (axioms)
 accepted idea om geometry
 theory
 idea that has to be proven or justified
 Postulate (a)
 through any 2 points there is exactly one line (2 points determine a line)
 Postulate (b)
 If 2 lines intersect, they intersect at exactly one point
 Postulate (c)
 If 2 planes intersect, they intersect at exacly one line
 Postulate (d)

Through any 3 noncollinear points there is exactly 1 plane
(three noncollinear points determine a plane)  segment
 a part of a line consisting of 2 endpoints and all the points in between them
 ray
 a part of a line consisting of 1 endpoint and all the points of the line on 1 side of the endpoint
 opposite rays

2 collionear rays with the same endpoint
opposite rays always form a line  parallel lines
 coplanar lines that do not intersect
 skew lines
 noncoplanar lines
 parallel planes
 planes that never meet
 Ruler Postulate:
 If you have a number line, all the points on that line have a 1 to 1 correspondence to the numbers on the line
 congruent

2 segments of the same length
If _AB is congruent to _CD then AB=CD and if AB=CD then _AB=_CD  midpoint

a midpt. of a segment is a point that divides a segment into 2 congruent segments (or two segments of equal length)
B is the midpt. of _AC if _AB=_BC and B is in between A and C (and visa versa)  Segment Addition Postulate
 If A,B,C are collinear and B is between A and C then AB+BC=AC
 angle

union of 2 rays w/ a common endpt.
the rays are the sides of the angle. The endpt. is the vertex of the angle  Protractor Postulate
 If you look at all the possible angle measures between 0 and 180 and all the possible sized angles between a ray folded onto itself and a pair of opposite rays, there will be a 1 to 1 correspondence between the angle measures and the angles themselves
 Angle Addition Postulate

If a point B is in the interior of <AOC then m<AOB + m<BOC = m<AOC
If <AOC is a straight angle then m<AOB+m<BOC =180  Congruent Angles
 angles with the same measure
 constructions
 a way to create geometric objects using a straightedge and a compass
 perpendicular lines
 lines that intersect to form right angles
 perpendicular bisector of a segment
 a line, segment or ray that is perpendicular to a segment at its midpoint