UNIT 1 Definitions
These are the important skills that we must begin with: the building formative and foundational skills. |
-Collinear: 2 or more points are collinear if and only if a line can be drawn to contain them. 2 points are always collinear. 3 and more points are sometimes collinear.
-Coplanar: 2 or more points are coplanar if and only if a plane can be drawn to contain them. 3 points are always coplanar (ex-tripod). 4 or more points are sometimes coplanar. -Network: a collection of points with interconnecting paths -Path: a line or curve connected to points -Node: a junction point among paths in a network. -Intersecting: 2 or more objects are intersecting if and only if they share at least 1 point. -Parallel: 2 or more lines are parallel if and only if they a) are coplanar and b) never intersect. -Skew: 2 or more lines are skew if and only if they a) are non-coplanar and b) never intersect. -Inductive Reasoning: using patterns to create a reasonable conclusion. -Deductive Reasoning: using known facts to create true conclusion. -Congruence: used to compare two "whole" objects only (symbol is a squiggly line over an equal sign) -Equality: used to compare two explicit quantities (lengths, heights, etc.) - uses measurements of lines, segments, and rays; numbers, and adding, multiplying, division, and subtraction (congruence uses none of these) -Postulate: a rule that we accept as true without proof-"well, duh!" -Theorem: a rule that can be (has been) proven to be true -Ruler Postulate: we can measure the distance between A and B (find length AB) by taking the absolute value of difference between their coordinates on a number line. AB= absolute value of a-b -Segment Addition Postulate: If B is collinear with and between A and C, then AB+BC=AC -Midpoint Definition: M is the midpoint of line AB if AM=Mb and Mis on line AB. -Midpoint Theorem: If M is the midpoint of line AB, then AM=Mb=1/2 AB. -Unique Midpoint Postulate: every segment has exactly one midpoint. |
![Picture](/uploads/5/9/2/3/59231587/1442549322.png?250)
Copy a Segment and Segment Addition:
-I've included a picture of the work we did in class with segments.
-we used a compass and lined up the tips of the compass with each endpoint
-then, we made a long line, and marked where the endpoints were (according to the compass) and drew those points, calling them copy A and B (letter with little ' next to it)
-Using a compass, you can easily copy and add segments
-I've included a picture of the work we did in class with segments.
-we used a compass and lined up the tips of the compass with each endpoint
-then, we made a long line, and marked where the endpoints were (according to the compass) and drew those points, calling them copy A and B (letter with little ' next to it)
-Using a compass, you can easily copy and add segments
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