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Details matter when naming things in Geometry! You must consider how the symbol is written: Capital letters / lowercase Print / cursive How many letters used Order of letters With an extra symbol or without Some things have more than one way to name them Name Point Symbols Like… One CAPITAL print letter: A Simple Definition A dot; a location on a graph Picture Name Line Symbols (2 methods!) Simple Definition two capital letters with double arrow on top: A string of points that AB line up and continue single lowercase forever in cursive letter both with nothing else: directions Picture Name line segment Symbols the two endpoints are CAPITALIZED with a bar on top, in either order: AB or BA Simple Definition Part of a line, has two endpoints Picture A B Name Symbols Simple Definition Half of a line, has one endpoint ray AB Must be written first Picture Name angle Symbols (3 methods!) Simple Definition With a number: 1 With three letters (vertex in middle): ABC or CBA With the vertex only (unless more than one angle uses same vertex): B Picture A Two rays that have a common endpoint connecting them B C vertex Name plane Symbols (2 methods!) Simple Definition Picture One CAPITAL CURSIVE letter : M Any three points in the plane as long as they are not on the same line: ABC (order does not matter, must be CAPITALIZED) A flat surface that extends forever A B C M OTHER SYMBOLS The measure of a segment tells how long it is. It is shown by removing the bar and just using the two letters: AB The measure of an angle tells how many degrees it has. It is shown by putting a small “m” in front of the angle’s name: mABC Congruent means two things have the same measure. It looks like an equal sign with an extra squiggle on top: Additional Vocabulary: Collinear points are points that lie on the same line. Coplanar points are points that lie on the same plane. - Share a common starting point and go in opposite directions to form a line intersection – where things meet or cross Now work on SYMBOL PRACTICE # 1 Geometry Symbols Practice # 1 Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". (Answers next page.) 1. location in space; no actual size 2. part of a line between two endpoints 3. "half of a line" extending in one direction forever 4. an infinite string of points; has no actual thickness 5. flat surface that extends indefinitely in all directions; no actual thickness Geometry Symbols Practice # 1 Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". 1. location in space; no actual size point 2. part of a line between two endpoints line segment 3. "half of a line" extending in one direction forever ray 4. an infinite string of points; has no actual thickness line 5. flat surface that extends indefinitely in all directions; no actual thickness plane Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". (Answers next page.) 6. one CAPITAL letter cursive letter 8. single UPPERCASE Cursive letter 7. single lower-case, 9. two CAPITAL letters with → on top 10. three CAPITAL letters with no other symbol 11. two printed CAPITAL letters with ↔ on top 12. two CAPITAL letters with a — on top Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". 6. one CAPITAL letter point cursive letter line 8. single UPPERCASE Cursive letter plane 7. single lower-case, 9. two CAPITAL letters with → on top ray 10. three CAPITAL letters with no other symbol plane 11. two printed CAPITAL letters with ↔ on top line 12. two CAPITAL letters with a — on top segment Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". (Answers next page.) Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". plane line point angle ray segment Measure of an angle angle Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". (Answers next page.) Tell if each is a point, line, plane, line segment, ray, angle, measure of a line segment, measure of an angle, or "nothing". plane segment line ray line point NOTHING plane Arrow wrong way Measure of a segment Measure of an angle line segment angle NOTHING No bar over planes angle Measure of an angle NOTHING Planes capitalized NOTHING With arrow, lines must be capitalized; if cursive, use one small letter and no arrow Answers next page. Answers next page. It must be the vertex. It must be the endpoint. It should not be from the side with the arrow.