Definitions. You can represent a point by a dot and name it by a capital letter.

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Lilian Singleton
5 years ago
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1 Definitions Name Block Term Definition Notes Sketch Notation Point A location in space that is represented by a dot and has no dimension You can represent a point by a dot and name it by a capital letter. A Line Is represented by a straight path that extends in two opposite directions without end and has no thickness. A line contains infinitely many points. You can name a line by any two points on the line such as AB (read line AB ) or BA, or by a single lowercase letter, such as line l. AB or BA BC or CB AC or CA Line l Plane Is represented by a flat surface that extends without end and has no thickness. A plane contains infinitely many lines. You can name a plane by a capital letter, such as plane P, or by at least three points in the plane that do not all lie on the same line, such as plane ABC. P ABC ACB BCA BAC CAB CBA Pg. 1

2 Collinear Points Points that lie on the same line. Name the points same way as you would normally with a point by using a single capital letter. A B C D Coplanar Points Points that lie in the same plane. Name the same way as you would name a point. A B C Coplanar Lines Lines that line in the same plane. Name the same way as you would name a line. AB or BA CD or DC EF or FE Segment or Line Segment Part of a line that consists of two endpoints and all points between them. You can name a segment by its two endpoints such as AB (read as segment AB ) or. BA AB BA Pg. 2

3 Ray Part of a line that consists of one endpoint and all the points of the line on one side of the endpoint. You can name a ray by its endpoint and another point on the ray, such as AB (read as ray AB ). The order of the points indicates the ray s direction. AB AC BA CA Opposite Rays Two rays that share the same endpoint and form a line. You name opposite rays in pairs, by their shared endpoint and any other point on each ray. BA with BC AB with CB BA with CB AB with BC In a statement, we use to show two segments are congruent. Congruent Segments Segments that are the same length. On a sketch, we use tick marks of the same number on the segments. It is NOT correct to say the segments are equal. Numbers are equal. Objects are congruent. AB CD Pg. 3

4 Midpoint A point that divides a segment into two congruent segments. You must put tick marks on both sides of the midpoint so show the segments are congruent. To name the midpoint you name it as you would a point with one capital letter. B is the midpoint of AC Segment bisector A line, segment, ray or plane that intersects a segment at its midpoint. You must put tick marks on both sides of the midpoint so show the segments are congruent. Line l is the segment bisector of AC. Angle Formed by two rays with the same endpoint. To name an angle you must include the angle symbol and then you have some choices: By the vertex (if there are only two rays at one vertex). 3 letters (one from each ray and the vertex) with the vertex as the middle letter (when there are more than two rays at a vertex). A number (if given in the interior of the angle. A BAC 1 Pg. 4

5 Acute Angle An angle whose measure is between 0 and 90. You name acute angles the same way you name angles. When sketching, be sure to make it look obviously acute or include an angle measure that is between 0 and 90. B ABC 1 Right Angle An angle whose measure is 90. Name right angles the same way you name angles. When sketching be sure to include the right angle mark or write in 90 for the angle. B ABC Obtuse Angle An angle whose measure is greater than 90 but less than 180. You name obtuse angles the same way you name angles. When sketching, be sure to make it look obviously obtuse or include an angle measure that is greater than 90 but less than 180. B ABC 1 Pg. 5

6 Straight Angle An angle whose measure is 180. Name straight angles the same way you name angles. When sketching be sure it looks like a line. B ABC Congruent Angles Angles with the same measure. You must have the congruency marks or degree measures of the same value to show that two angles are congruent. You name congruent angles the same way you name angles. A B Angle Bisector A ray that divides an angle into two congruent angles. Since it is a ray, you name the angle bisector like you would a ray. Be sure to include congruency tick marks on the sketch to indicate the angles are congruent. AY is the angle bisector of XAZ Therefore, XAY ZAY Space The set of all points in three dimensions. N/A N/A Pg. 6

7 Term Definition Notes Sketch Complementary Angles Two angles whose measures have a sum of 90 Could be adjacent angles OR they can be completely separate. Be sure to give angle measures on a sketch that add up to 90 Supplementary Angles Two angles whose measures have a sum of 180 Could be adjacent angles OR they can be completely separate. Be sure to give angle measures on a sketch that add up to 180 Adjacent Angles Two coplanar angles with a common side, a common vertex, and no common interior points. Must be named with 3 letters OR numbers if provided Pg. 7

8 Term Definition Notes Sketch A pair of adjacent angles whose noncommon sides are opposite rays. Angles must be named with three letters or numbers if provided. Linear Pair The angles of a linear pair form a straight angle Looks like a line with a ray sticking out of it. Vertical Angles Two angles whose sides form two pairs of opposite rays Must be named with 3 letters or numbers if provided Pg. 8

Euclid. Father of Geometry Euclidean Geometry Euclid s Elements

Euclid. Father of Geometry Euclidean Geometry Euclid s Elements Euclid Father of Geometry Euclidean Geometry Euclid s Elements Point Description Indicates a location and has no size. How to Name it You can represent a point by a dot and name it by a capital letter.